100BASE-T Ethernet cabling system designed to run at 100 Mbps on twisted pair cabling. Also called Fast Ethernet.

1000BASE-T Ethernet cabling system designed to run at 1000 Mbps on twisted pair cabling. Also called Gigabit Ethernet.

1000BASE-TX Similar to 1000BASE-T but uses two pairs of wires rather than four. Not as commonly used as 1000BASE-T.

10GBASE-T Ethernet standard that supports speeds of up to 10 Gbps and is common on server-to-server connections. Requires Cat 6 or better twisted pair or fiber optic cabling.

2-in-1 Portable devices that serve as both a laptop and a tablet.

3G Third-generation cellular data technologies (such as EV-DO, UTMS, HSPA+, and HSDPA) with real-world speeds under 10 Mbps.

4G Fourth-generation cellular data technologies. Most popularly implemented as Long Term Evolution (LTE), a wireless data standard with theoretical download speeds of 1 Gbps and upload speeds of 100 Mbps.

5G Fifth-generation cellular data technologies, launched in 2019. Their specifications call for up to 20 Gbps, but real-world speeds are often less and can vary depending on the carrier and location.

64-bit processing A type of processing that can run a compatible 64-bit operating system, such as Windows 10 and 11, and 64-bit applications. 64-bit PCs have a 64-bit-wide address bus, enabling them to use more than 4 GB of RAM.

802.11a Wireless networking standard that operates in the 5-GHz band with a theoretical maximum throughput of 54 Mbps.

802.11ac Wireless networking standard that operates in the 5-GHz band and uses multiple in/multiple out (MIMO) and multi-user MIMO (MU-MIMO) to achieve a theoretical maximum throughput of 1+ Gbps.

802.11ax Wireless networking standard that operates in the 2.4-, 5-, and 6-GHz bands. Also known as high-efficiency wireless, it introduces improvements that optimize congested networks and reduce power use on client devices. The main improvement is the introduction of the 6-GHz band, which supports more channels, is less saturated, and suffers less interference. Also known as Wi-Fi 6 or Wi-Fi 6E (if it supports the 6-GHz band).

802.11b Wireless networking standard that operates in the 2.4-GHz band with a theoretical maximum throughput of 11 Mbps.

802.11g Wireless networking standard that operates in the 2.4-GHz band with a theoretical maximum throughput of 54 Mbps and is backward compatible with 802.11b.

802.11n Wireless networking standard that can operate in both the 2.4-GHz and (optionally) 5-GHz bands and uses multiple in/multiple out (MIMO) to achieve a theoretical maximum throughput of 100+ Mbps.

AC (alternating current) Type of electricity in which the flow of electrons alternates direction, back and forth, in a circuit.

acceptable use policy (AUP) Defines what actions employees may or may not perform on company equipment, including computers, phones, printers, and even the network itself. This policy defines the handling of passwords, e-mail, and many other issues.

access control list (ACL) A clearly defined list of permissions that specifies what actions an authenticated user may perform on a shared resource.

access control vestibule Small room with a set of doors—one to the unsecured area and one to a secured area. Only one door can open at a time, and individuals must authenticate to continue through the door to the secured area. Combats tailgating. Also commonly known as a mantrap.

access point See WAP.

Accounts (Windows Settings) Windows Settings category that includes e-mail and account options.

activation (software) Process of confirming that an installed copy of a Microsoft product (most commonly Windows or a Microsoft Office application) is legitimate. Usually done at the end of software installation.

active partition On a hard drive, the primary partition that contains an operating system.

actively listen Part of respectful communication involving listening and taking notes without interrupting.

activity light An LED on a NIC, hub, or switch that blinks rapidly to show data transfers over the network.

Address Resolution Protocol (ARP) Protocol in the TCP/IP suite used with the command-line utility of the same name (arp) to determine the MAC address that corresponds to a particular IP address.

administrative shares Administrator tool to give local admins access to hard drives and system root folders.

Administrative Tools Group of Control Panel applets, including Computer Management, Event Viewer, Performance Monitor, and Task Scheduler.

administrator account User account, created when the OS is first installed, that is allowed complete, unfettered access to the system without restriction.

administrator password Credentials for the system administrator account.

Administrators group List of members with complete administrator privileges.

ADSL (asymmetric digital subscriber line) Fully digital, dedicated connection to the telephone system that provides average download speeds of 3–15 Mbps and upload speeds of 384 Kbps to 1.5 Mbps. Asymmetric identifies that upload and download speeds are different, with download usually being significantly faster than upload.

Advanced Encryption Standard (AES) A block cipher created in the late 1990s that uses a 128-bit block size and a 128-, 192-, or 256-bit key size. Practically uncrackable.

Advanced Micro Devices (AMD) See AMD.

AirDrop Apple feature for its various operating systems that enables easy wireless sharing of files between Apple devices.

algorithm Set of rules for solving a problem in a given number of steps.

AMD (Advanced Micro Devices) CPU and chipset manufacturer that competes with Intel. Produces FX, A-Series, Ryzen, and Opteron CPUs and APUs. Also produces video card processors (GPUs) under its Radeon brand.

amperage See current.

amperes (amps or A) Unit of measure for amperage, or electrical current.

analog Device that uses a physical quantity, such as length or voltage, to represent the value of a number. By contrast, digital storage relies on a coding system of numeric units.

Android application package (APK) Installation software for Android apps.

ANSI/TIA A major telecommunication standards agency. The Telecommunication Industry Association (TIA) establishes the UTP categories under the ANSI/TIA 568 specification. The American National Standards Institute (ANSI) accredits TIA standards to ensure compatibility of industry and international standards. See also UTP.

anti-malware program Software designed to identify and block or remove malware. Typically powered by frequently updated definition files containing the signatures of known malware.

antistatic bag Bag made of antistatic plastic into which electronics are placed for temporary or long-term storage. Used to protect components from electrostatic discharge.

antistatic mat Special surface on which to lay electronics to prevent electrostatic discharge. Includes a grounding connection designed to equalize electrical potential between a workbench and one or more electronic devices.

antistatic wrist strap Special device worn around the wrist to prevent electrostatic discharge. Includes a grounding connection designed to equalize electrical potential between a technician and an electronic device.

antivirus program Software designed to combat viruses by either seeking out and destroying them or passively guarding against them. Typically, it is frequently updated with new definition files to enable up-to-date protection from newly discovered viruses.

API (application programming interface) Enables computer programs to “talk” to each other. Unlike a user interface, an API is not visible to the user. Documented APIs enable one vendor to create software that can communicate with another vendor’s software.

APIPA (Automatic Private IP Addressing) Feature of Windows that automatically assigns an IP address to the system when the client cannot obtain an IP address automatically. See also zeroconf.

App Store Apple’s mobile software storefront, where you can purchase apps for your smartphone, tablet, and other Apple products.

Apple File System (APFS) Apple’s proprietary file system, introduced to replace the older HFS+.

applet Generic term for a program in the Windows Control Panel.

application manager Mobile device interface for removing and managing apps running on the device.

application programming interface See API.

application spoofing The act of disguising a malicious mobile app as a legitimate one for the purpose of infecting a target device with malware or stealing credentials like passwords.

application virtualization Process that virtualizes OS capabilities that an application would normally use to install and do its work. Enables the use of an application without actually installing it, running an application that only works on an older OS version, or even running an application that only works on a different OS.

Applications Tab in Task Manager that lists running applications.

Apps (Windows Settings) Windows settings category that enables you to list, view, manage autostart, and uninstall apps.

Apps & features Area of the Windows 10 Settings Apps category that enables users to add and remove programs and Windows features.

apt-get Linux command for installing or updating a program using the advanced packaging tool.

ARM (Advanced RISC Machine) Energy-efficient processor design frequently used in mobile devices and also used by the latest macOS computers using the M1 and M2 processors.

ARP See Address Resolution Protocol.

aspect ratio Ratio of width to height of a display. Wide-screen displays such as modern TVs, desktop computer monitors, portable computer displays, and even smartphones commonly use 16:9 or 16:10, although you can find devices with many other aspect ratios.

assertive communication Means of communication that is not pushy or bossy but is also not soft. Useful in dealing with upset customers as it both defuses their anger and gives them confidence that you know what you’re doing.

asset tag Inventory tracking tags (which may be simple barcodes or use wireless networking protocols such as RFID) that help an organization track items such as equipment.

attack vector The route or methods used by a given attack (including malware).

attributes Values in a file that determine the hidden, read-only, system, and archive status of the file.

ATX (Advanced Technology Extended) Popular motherboard form factor that generally replaced the AT form factor.

audio jack Very popular connector used to transmit two audio signals; perfect for stereo sound. Confusingly, you can find the diameter described as both 1/8 inch and 3.5 mm.

AUP See acceptable use policy.

authentication The process of identifying and granting access to some user trying to access a system.

authorization The process that defines which resources an authenticated user may access and what the user may do with those resources.

AutoPlay A Windows feature that opens a dialog box when removable media is inserted into the computer, providing options based on what Windows finds on the drive, including starting the Autorun application.

Autorun A feature that enables Windows to look for and read a file called autorun.inf immediately after a removable media device (optical disc or thumb drive) is inserted and automatically run whatever program the file lists.

Backup and Restore Windows 7’s backup utility. It offers two options: create a backup or restore from a backup. Windows 10 still supports making and restoring these backups, which it calls Backup and Restore (Windows 7). See also File History.

backup testing The process of ensuring that file or system backups have produced backups from which you can restore usable systems and files.

badge reader See smart card reader.

bandwidth The capacity of a network to transmit a given amount of data during a given period.

bash Default command shell on macOS and most Linux distributions. See shell.

basic disk Hard drive partitioned in the “classic” way with a master boot record (MBR) and partition table. See also dynamic disks.

battery health The amount of charge a battery can hold. Decreases over time as the battery is charged and discharged.

battery life The length of time a battery can be used before needing to be recharged.

binary numbers Number system with a base of 2, unlike the number systems most of us use that have bases of 10 (decimal numbers), 12 (measurement in feet and inches), and 60 (time). Binary numbers are preferred for computers for precision and economy. An electronic circuit that can detect the difference between two states (on–off, 0–1) is easier and more inexpensive to build than one that could detect the differences among ten states (0–9).

biometric authentication Authentication process using biometric data such as voice, fingerprints, or retinal scans.

biometric scanner Hardware device used to support authentication; works by scanning and remembering a unique aspect of a user’s body part (e.g., retina, iris, face, or fingerprint) by using some form of sensing device such as a retinal scanner.

BIOS (basic input/output services) (basic input/output system) Classically, software routines burned onto the system ROM of a PC. More commonly seen as firmware that directly controls a particular piece of hardware. This firmware handles startup operations and low-level control of hardware such as disk drives, the keyboard, and monitor.

bit Single binary digit. Also, any device that can be in an on or off state.

BitLocker Drive Encryption Drive encryption software offered in high-end versions of Windows. BitLocker requires a special chip to validate hardware status and to ensure that the computer hasn’t been hacked.

Bluetooth Wireless technology designed to create small wireless networks preconfigured to do specific jobs, but not meant to replace full-function networks or Wi-Fi.

Blue Screen of Death (BSoD) Infamous error screen that appears when Windows encounters an unrecoverable error. This is an example of a proprietary crash screen.

bollard Short post made of metal, concrete, or another solid material used to prevent vehicles from entering or driving onto an area. Often used to protect pedestrian areas or deny vehicles from getting too close to a secure area.

boot To initiate an automatic routine that clears the memory, loads the operating system, and prepares the computer for use. Term is derived from “pull yourself up by your bootstraps.” Necessary because RAM doesn’t retain program instructions when power is turned off.

boot method Media a computer uses to initiate the booting process. Includes optical media, removable drives, or a networked location. For the related CMOS setting, see boot sequence.

boot options Settings in the system setup program that define which devices the system will attempt to boot from (and in what order).

boot sector First sector on a storage drive. The boot-up software in ROM tells the computer to load whatever program is found there. If a system disk is read, the program in the boot record directs the computer to the root directory to load the operating system.

bootable disk Any storage device with a self-starting operating system.

bootleg application Fake application designed to trick users into installing it. See also application spoofing.

bootmgr Windows Boot Manager. Manages the boot process using information from the Boot Configuration Data (BCD) file.

bootrec A Windows Recovery Environment troubleshooting and repair tool that repairs the master boot record, boot sector, or BCD store.

botnet Network of computers infected with malware that can be controlled to do the bidding of the malware developers, or anyone who pays them. A common use is carrying out distributed denial of service (DDoS) attacks.

broadband Commonly understood as a reference to high-speed, always-on communication links that can move large files much more quickly than a regular phone line.

broadcast A network transmission addressed for every node on the network.

broadcast domain Group of computers connected by one or more switches––that is, a group of computers that receive broadcast frames from each other.

browser Program specifically designed to retrieve, interpret, and display Web pages.

brute-force attack Simple attack that attempts to guess credentials or identify vulnerabilities by trying many possibilities.

BSoD See Blue Screen of Death.

bug Programming error that causes a program or a computer system to perform erratically, produce incorrect results, or crash. The term was coined when a real bug was found in one of the circuits of one of the first ENIAC computers.

bus Series of wires connecting two or more separate electronic devices, enabling those devices to communicate. Also, a network topology where computers all connect to a main line called a bus cable.

BYOD (bring your own device) An organizational policy that permits employees to use their own phones or other mobile devices instead of company-issued ones.

byte Unit of 8 bits; fundamental data unit of personal computers. Storing the equivalent of one character, the byte is also the basic unit of measurement for computer storage.

cable Internet Fast Internet connection from a cable TV provider via RG-6 or RG-59 cable and a cable modem.

cable lock Simple anti-theft device for securing a laptop to a nearby object.

cable modem Device that enables Internet connection over existing coaxial cable television infrastructure by translating signals into a form that networked devices can understand.

cable tester Device for verifying that the connectors and wires in a cable (such as UTP) are in good order.

cache (disk) Special area of RAM that stores the data most frequently accessed from the hard drive. Cache memory can optimize the use of your systems.

cache (L1, L2, L3, etc.) Special section of fast memory, usually built into the CPU, used by the onboard logic to store information most frequently accessed by the CPU.

calibration Process of matching the print output of a printer to the visual output of a monitor.

card reader Device with which you can read data from one of several types of flash memory.

Cat 5 Category 5 wire; an ANSI/TIA standard for UTP wiring that can operate at up to 100 Mbps.

Cat 5e Category 5e wire; ANSI/TIA standard for UTP wiring that can operate at up to 1 Gbps.

Cat 6 Category 6 wire; ANSI/TIA standard for UTP wiring that can operate at up to 10 Gbps.

Cat 6a Category 6a wire; augmented Cat 6 UTP wiring that supports 10-Gbps networks at the full 100-meter distance between a node and a switch.

Cat 7 Supports 10-Gbps networks at 100-meter segments; shielding for individual wire pairs reduces crosstalk and noise problems. Cat 7 is not an ANSI/TIA standard.

catastrophic failure A failure in which a component or whole system will not boot; usually related to a manufacturing defect of a component. Could also be caused by overheating and physical damage to computer components.

cd Command-line utility for changing the focus of the command prompt from one directory to another. Shorthand for “change directory.”

cellular location services Mobile device feature that can detect the device’s location, enabling apps to request and use this information to provide location-aware services, such as finding nearby restaurants.

certificate authority (CA) Trusted entity that signs digital certificates to guarantee that the certificate was signed by the Web site in question (and not forged).

chain of custody A documented history of who has been in possession of a system or component.

change board A group of representatives from around the organization who review and approve change proposals.

change documentation Collected documentation for all aspects of a change process, including plans leading up to the change as well as receipts, overtime documents, an inventory of changed systems, a list of created users, and signed end-user acceptance forms.

change management A well-defined process composed of many planning and execution steps that enables organizations to change their IT infrastructure in a safe, cost-effective manner.

checksum Value generated from some data, like a file, and saved for comparing to other checksums later. Can be used to identify identical data, such as files on a user’s system that match known viruses. Checksums can also be used to monitor whether a program is changing itself over time, which is a strong warning sign that it may be malware that evolves to avoid detection.

chipset Electronic chips, specially designed to work together, that handle all of the low-level functions of a PC. In the original PC, the chipset consisted of close to 30 different chips. For most of the 1990s and 2000s, chipsets usually consisted of one, two, or three separate chips embedded into a motherboard. Today’s CPUs have controllers built in, such as the memory and display controllers. Almost all chipsets are now a single chip.

chkdsk (checkdisk) Hard drive error detection and, to a certain extent, correction utility in Windows, launched from the command-line interface. Originally a DOS command (chkdsk.exe); also the executable for the graphical Error checking tool.

chmod Linux command used to change user and group permissions for a file.

chown Linux command used to change ownership over a directory or file.

Chrome OS Google’s Linux-based operating system designed to connect users via the Internet into Google applications, such as Gmail, Google Docs, and more. Chrome OS comes preinstalled on purpose-built hardware such as the Chromebook portable computers.

Chromebook Strictly, any portable computer running Google’s Chrome OS. Chromebooks offer an experience focused on Web applications by making use of virtually unlimited data storage in the cloud and Software as a Service (SaaS) applications available over the Web. Because they offload so much work, Chromebooks have a reputation for being cheap and light, but premium Chromebooks are increasingly common.

Classless Inter-Domain Routing (CIDR) Current system for creating and notating IPv4 subnets; replaced the older, less flexible three-class system.

clean installation Installing an operating system on a fresh drive, following a reformat of that drive. Often it’s the only way to correct a problem with a system when many of the crucial operating system files have become corrupted.

clearing cache The process of clearing stored app or browser settings in order to resolve performance issues. Commonly used to resolve issues with Web browsers or to free up resources on mobile devices.

client Computer program that uses the services of another computer program. Also, software that extracts information from a server; a Web browser is a client, and the Web site that it accesses is the server. Also, a machine that accesses shared resources on a server.

client/server Relationship in which client software obtains services from a server on behalf of a person.

client-side virtualization Using a hypervisor installed on a client machine to run a virtual machine. The VM may be created and stored on the client machine or accessed over the network.

clock cycle Single charge to the clock wire (CLK) of a CPU, informing the CPU that another piece of information is waiting to be processed.

clock speed The maximum number of clock cycles that a CPU can handle in a given period of time, measured in MHz or GHz. In modern CPUs, the internal speed is a multiple of the external speed. See also clock-multiplying CPU.

clock-multiplying CPU CPU that takes the incoming clock signal and multiples it inside the CPU to let the internal circuitry of the CPU run faster.

cloud computing A model for enabling and accessing computing storage and other shared (or not shared) resources on demand. The “cloud” is based on servicing models that include, among others, Infrastructure as a Service (IaaS), Platform as a Service (PaaS), and Software as a Service (SaaS), as well as hybrid mixtures of these services.

CMOS (complementary metal-oxide semiconductor) Defunct technology used in earlier computer systems that hooked up a small amount of RAM to a small battery to hold system settings for the BIOS firmware even with the computer off. This has long since been incorporated into the chipset. CMOS is often informally used to refer to the CMOS setup program or system setup utility.

CMOS battery A coin cell lithium-ion battery that maintains power to the CMOS memory chip when the computer is otherwise unpowered. The usual battery size is CR2032.

CMOS clear A jumper setting or button on the motherboard that, when set, will revert CMOS settings to the factory defaults. Sometimes labeled CLRTC on the motherboard.

CMOS setup program Program enabling you to access and update CMOS data. Also referred to as the system setup utility, BIOS setup utility, UEFI/BIOS setup, and similar names.

coaxial cable Cabling in which an internal conductor is surrounded by another, outer conductor, thus sharing the same axis.

code Set of symbols representing characters (e.g., ASCII code) or instructions in a computer program (a programmer writes source code, which must be translated into executable or machine code for the computer to use).

code-division multiple access (CDMA) Wireless data standard for mobile devices.

color depth (display) The number of bits (the bit depth) necessary to represent the number of colors in a graphics mode. Common color bit depths are 16-bit and 32-bit, representing 65,536 colors and 16.7 million colors (plus an 8-bit alpha channel for transparency levels), respectively.

command A request, typed from a terminal or embedded in a file, to perform an operation or to execute a particular program.

command prompt Text prompt for entering commands.

command-line interface (CLI) Text user interface. Users input text commands and receive text output. CLI commands, which are more flexible and often faster (or use fewer resources) than a graphical equivalent, are also easy to compose into scripts for performing frequent tasks.

community cloud Cloud network that serves a community or group with shared needs and interests, such as hospitals or defense contractors.

compatibility modes Feature of Windows to enable software written for previous versions of Windows to operate in newer versions.

compliance Concept that members of an organization must abide by the rules created by and applying to that organization (including government regulations). For a technician, compliance often defines what software can or cannot be installed on an organization’s computers.

component failure Occurs when a system device fails due to a manufacturing defect or some other type of defect.

compression Process of squeezing data to eliminate redundancies, allowing files to use less space when stored or transmitted.

Computer Management Applet in Windows’ Administrative Tools that contains several useful snap-ins, such as Device Manager and Disk Management.

connector Small receptacle used to attach a cable to a device or system. Common types of connectors include USB, PS/2, RJ-45, VGA, HDMI, DVI, HD15, DisplayPort, and Thunderbolt.

consumables Materials used up by printers, including paper, ink, ribbons, 3-D printer filament, and toner cartridges.

container file A file that contains multiple data streams, such as a ZIP archive file or an MP4 movie file. Also called a wrapper.

context menu Small menu brought up by right-clicking on objects in Windows.

contrast ratio Difference in intensity between the lightest and the darkest spot that a device can display (in the case of a monitor) or capture (in the case of a camera or scanner).

Control Panel Collection of Windows applets, or small programs, that can be used to configure various pieces of hardware and software in a system.

controller card Card adapter that connects devices, such as a drive, to the main computer bus/motherboard.

copy command Command-line tool used to make a copy of a file and paste it in another location.

counter Used to track data about a particular object when using Performance Monitor.

cp Copy command in Linux.

CPU (central processing unit) “Brain” of the computer. Microprocessor that handles primary calculations for the computer. CPUs are known by names such as Core i7 and Ryzen.

CRC See cyclic redundancy check.

credit card reader Device that can be attached to mobile phones and tablets to take credit card payments.

crimper A specialized tool for connecting network cables to a connector, such as twisted pair wires to an RJ-45 connector or coaxial cable to an RG-6 connector. Also called a crimping tool.

cross-site scripting (XSS) An attack in which the attacker injects malicious code into a Web app in order to trick it into sending things that it shouldn’t to other users of the Web app.

cryptominer A form of malware that enlists the hardware of the target system to mine cryptocurrency without the knowledge of the system’s owner.

CSMA/CA (carrier sense multiple access/collision avoidance) Networking scheme used by wireless devices to transmit data while avoiding data collisions, which wireless nodes have difficulty detecting.

CSMA/CD (carrier sense multiple access/collision detection) Networking scheme used by Ethernet devices to transmit data and resend data after detection of data collisions.

current Amount of electrons moving past a certain point on a wire, measured in units called amperes. Also called amperage.

cyclic redundancy check (CRC) Very accurate mathematical method used to check for errors in long streams of transmitted data. Before data is sent, the main computer uses the data to calculate a CRC value from the data’s contents. If the receiver calculates from the received data a different CRC value, the data was corrupted during transmission and is resent. Ethernet packets use the CRC algorithm in the FCS portion of the frame.

DAC See discretionary access control.

data classification System of organizing data according to its sensitivity. Common classifications include public, highly confidential, and top secret.

Data Collector Sets Windows log repository that accepts log entries from other Windows computers.

data roaming A feature of cellular data systems that enables the signal to jump from cell tower to cell tower and from your provider to another provider without obvious notice.

data storage Saving a permanent copy of your work so that you can come back to it later.

data usage cap Restrictions on how much data a user may consume. Once the user exceeds the limit, data may be blocked entirely or bandwidth may be throttled.

database system A representation of the relationship between two or more objects. Often used in asset management to keep track of who has possession of various assets and why they have them.

DB-9 A two-row DB connector (male) used to connect the computer’s serial port to a serial-communication device such as a modem or a console port on a managed switch.

DC (direct current) Type of electricity in which the flow of electrons is in a complete circle in one direction.

DDoS (distributed denial of service) An attack on a computer or network device in which multiple computers send data and requests to the device in an attempt to overwhelm it so that it cannot perform normal operations.

DDR3 SDRAM Type of SDRAM that sends 8 bits of data in every clock cycle.

DDR4 SDRAM Type of SDRAM that offers higher density and lower voltages than DDR3 and can handle faster data transfer rates. Maximum theoretical capacity of DDR4 DIMMs is up to 512 GB.

DDR5 SDRAM The successor to DDR4, offering doubled bandwidth, decreased power consumption, quadrupled DIMM capacity, and up to 7200 MT/s at the time of writing.

DE (desktop environment) Name for the various user interfaces found in Linux distributions.

debug To detect, trace, and eliminate errors in computer programs.

decrypt To pass decryption keys and encrypted data through the appropriate decryption algorithm in order to retrieve the original unencrypted data. See encryption.

dedicated server Machine that is not used for any client functions, only server functions.

default gateway In a TCP/IP network, the nearest router to a particular host. This router’s IP address is part of the necessary TCP/IP configuration for communicating with multiple networks using IP.

default user accounts/groups Users or groups that are enabled by default. Some, such as the guest account, represent a security risk.

definition file List of malware signatures that enables anti-malware programs to identify malware on your system and clean them. This file should be updated often. Also called a signature file.

defragmentation (defrag) Procedure in which all the files on a hard disk drive are rewritten on disk so that all parts of each file reside in contiguous clusters. The result is an improvement in disk speed during retrieval operations.

degaussing Data destruction procedure used to reduce or remove the electromagnetic fields that store data on magnetic hard drives.

del (erase) Command-line tool used to delete/erase files.

denial of service See DoS.

Desktop User’s primary interface to the Windows operating system.

desktop virtualization A traditional desktop operating system installed in a VM. See also virtual machine.

device charger Plugs into a power source and charges a device through one of its ports, such as USB or Lightning. Convenient for charging while the device stays on.

device driver Program used by the operating system to control communications between the computer and peripherals.

device encryption Enhances mobile device security by encrypting the device’s internal storage.

Device Manager Utility that enables techs to examine and configure all the hardware and drivers in a Windows PC. It is both an MMC snap-in and a Windows 10 Control Panel utility.

Devices (Windows Settings) Windows Settings category that enables users to make changes to attached devices such as printers, scanners, keyboard, and mouse.

DFS (distributed file system) A storage environment where shared files are accessed from storage devices within multiple servers, clients, and peer hosts.

DHCP See Dynamic Host Configuration Protocol.

diagnostics menu Hidden mobile device menu that contains tests and diagnostics for verifying the functionality of various device hardware.

dictionary attack Type of brute-force attack using a dictionary to guess things like usernames and passwords. Don’t think Webster’s—these dictionaries may be full of usernames and passwords that have leaked or been used as defaults over the years.

dig Linux command that queries DNS to enable troubleshooting and monitoring.

digital certificate Form in which a public key is sent from a Web server to a Web browser so that the browser can decrypt the data sent by the server.

digital rights management (DRM) Code schemes for enforcing what users can and can’t do with commercial software or digital media files.

digitizer The touchscreen overlay technology that converts finger and stylus contact into input data for the device to use.

dilithium crystal Controlling agent in a faster-than-light warp drive.

DIMM (dual inline memory module) 32- or 64-bit type of DRAM packaging with the distinction that each side of each tab inserted into the system performs a separate function. DIMMs come in a variety of sizes, with 184-, 240-, and 288-pin being the most common on desktop computers.

dipole antenna Standard straight-wire antenna that provides the most omnidirectional function.

dir Command-line tool used to display the entire contents of the current working directory.

direct burial Rating applied to shielded twisted pair (STP) cabling that indicates a thicker jacket and some form of waterproofing for use outdoors or underground.

direct LED backlighting Matrix of LEDs that illuminates a display from directly behind the display panel.

directory Another name for a folder.

discretionary access control (DAC) Authorization method based on the idea that there is an owner of a resource who may at his or her discretion assign access to that resource. DAC is considered much more flexible than mandatory access control (MAC).

Disk Cleanup (cleanmgre.exe) Utility built into Windows that can help users clean up their hard drives by removing temporary Internet files, deleting unused program files, and more.

Disk Defragmenter (dfrgui.exe) A program that maintains performance by rearranging chunks of data on a storage device to ensure chunks that comprise a file are stored contiguously. Filename is dfrgui.exe. Renamed to Optimize Drives in Windows 8 and up.

disk duplexing Type of disk mirroring using two separate controllers rather than one; marginally faster than traditional mirroring because one controller does not write each piece of data twice.

disk initialization A process that places special information on every hard drive installed in a Windows system.

Disk Management (dismgmt.msc) Snap-in available with the Microsoft Management Console that enables techs to configure the various disks installed in a system; available in Computer Management | Administrative Tools.

disk mirroring Process by which data is written simultaneously to two or more disk drives. Read and write speed is decreased, but redundancy in case of catastrophe is increased.

disk quota Application allowing network administrators to limit hard drive space usage.

disk striping Process by which data is spread among multiple (at least two) drives. Increases speed for both reads and writes of data. Considered RAID level 0 because it does not provide fault tolerance.

disk striping with parity Method for providing fault tolerance by writing data across multiple drives and then including an additional drive, called a parity drive, that stores information to rebuild the data contained on the other drives. Requires at least three physical disks: two for the data and a third for the parity drive. This provides data redundancy at RAID levels 5, 10, and 0+1 with different options.

disk thrashing Hard drive that is constantly being accessed due to lack of available system memory. When system memory runs low, a Windows system will utilize hard disk space as “virtual” memory, thus causing an unusual amount of hard drive access.

Disk Utility macOS tool that checks for hard drive errors.

display adapter Handles all the communication between the CPU and the monitor. Also known as a video card or graphics card.

Display Settings Windows utility that enables a user to change color schemes, font sizes, and other aspects of what appears on the computer monitor.

DisplayPort Digital video connector used by some Apple Mac desktop models and some PCs, notably from Dell. Designed by VESA as a royalty-free connector to replace VGA and DVI.

distended capacitors Failed capacitors on a motherboard, which tend to bulge out at the top. This was especially a problem during the mid-2000s, when capacitor manufacturers released huge batches of bad capacitors.

distributed denial of service See DDoS.

distribution (distro) A specific variant of Linux.

DLP (Data Loss Prevention) System or set of rules designed to stop leakage of sensitive information. Usually applied to Internet appliances to monitor outgoing network traffic.

DMZ See screened subnet.

DNS (Domain Name Service) TCP/IP name resolution system that translates a host name into an IP address. Uses UDP port 53.

DNS domain Specific branch of the DNS name space. Top-level domains (TLDs) include .com, .gov, and .edu.

docking station Device that provides a portable computer extra features such as an optical drive, in addition to legacy and modern ports. Similar to a port replicator. Also, a charging station for mobile devices.

document the findings, actions, and outcomes Recording each troubleshooting job: what the problem was, how it was fixed, and other helpful information. (Step 6 of 6 in the CompTIA troubleshooting methodology.)

domain Groupings of users, computers, or networks. In Microsoft networking, a domain is a group of computers and users that share a common account database and a common security policy. On the Internet, a domain is a group of computers that share a common element in their hierarchical name. Other types of domains exist—e.g., broadcast domain, etc.

domain controller A computer running Windows Server that stores a set of domain accounts.

domain-based network Network that eliminates the need for logging on to multiple servers by using domain controllers to hold the security database for all systems.

DoS (denial of service) An attack on a computer resource that prevents it from performing its normal operations, usually by overwhelming it with large numbers of requests in an effort to monopolize its resources.

DRAM (dynamic random access memory or dynamic RAM) Memory used to store data in most personal computers. DRAM stores each bit in a “cell” composed of a transistor and a capacitor. Because the capacitor in a DRAM cell can only hold a charge for a few milliseconds, DRAM must be continually refreshed, or rewritten, to retain its data.

drive cloning Taking a PC and making a duplicate of the hard drive, including all data, software, and configuration files, and transferring it to another PC. See also image deployment.

drive letter A letter designating a specific drive or partition.

driver signing Digital signature for drivers used by Windows to protect against potentially bad drivers.

DSL (digital subscriber line) High-speed Internet connection technology that uses a regular telephone line for connectivity. DSL comes in several varieties, including asymmetric (ADSL) and symmetric (SDSL), and many speeds. Typical home-user DSL connections are ADSL, with faster download speeds than upload speeds.

dual boot Refers to a computer with two operating systems installed, enabling users to choose which operating system to load on boot. Can also refer to kicking a device a second time just in case the first time didn’t work.

dual-channel architecture Using two sticks of RAM to increase throughput. See also triple-channel architecture and quad-channel architecture.

dual-channel memory Form of memory access used by many motherboards that requires paired identical sticks of RAM.

dumpster diving To go through someone’s trash in search of information.

duplexing Similar to mirroring in that data is written to and read from two physical drives for fault tolerance. Separate controllers are used for each drive, both for additional fault tolerance and for additional speed. Considered RAID level 1. Also called disk duplexing or drive duplexing.

duplexing assembly Mechanical feature of some printers that can automatically flip the paper to print on both sides.

DVI (digital visual interface) Special video connector designed for digital-to-digital connections; most commonly seen on PC video cards and LCD monitors. Some versions also support analog signals with a special adapter.

dynamic disks Special feature of Windows that enables users to span a single volume across two or more drives. Dynamic disks do not have partitions; they have volumes. Dynamic disks can be striped, mirrored, and striped or mirrored with parity.

Dynamic Host Configuration Protocol (DHCP) Protocol that enables client hosts to request and receive TCP/IP settings automatically from an appropriately configured server. Uses UDP ports 67 and 68.

ECC (error correction code) Special software, embedded on hard drives, that constantly scans the drives for bad blocks.

ECC RAM/DRAM (error correction code RAM/DRAM) RAM that uses special chips to detect and fix memory errors. Commonly used in high-end servers where data integrity is crucial.

effective permissions User’s combined permissions granted by multiple groups.

EFS (encrypting file system) Storage organization and management service, such as NTFS, that has the capability of applying a cipher process to the stored data. The professional editions of Windows offer a feature called the Encrypting File System (EFS), an encryption scheme that any user can use to encrypt individual files or folders on a computer.

electromagnetic interference (EMI) Electrical interference from one device to another, resulting in poor performance of the device being interfered with. Examples: static on your TV while running a blow dryer, or placing two monitors too close together and getting a “shaky” screen.

electromagnetic pulse (EMP) Potentially damaging burst of electromagnetic energy caused by events such as electrostatic discharge (ESD), lightning, nuclear detonations, and so on.

electrostatic discharge (ESD) Uncontrolled rush of electrons from one object to another. A real menace to PCs, as it can cause permanent damage to semiconductors.

eliciting answers Communication strategy designed to help techs understand a user’s problems better. Works by listening to a user’s description of a problem and then asking cogent questions.

embedded system A computer that is dedicated to a specific task and often is included as part of a larger and more complex system. Embedded systems are found in everything from medical devices to power plants to toys to railway control systems.

emergency notification Feature built into smartphones enabling them to receive messages from emergency broadcast systems, such as the Emergency Alert System (EAS) in the United States.

encrypted Data that has been passed through an encryption algorithm, rendering it unreadable without the decryption keys. See encryption.

encryption Making data unreadable by those who do not possess a key or password.

end process Option in Task Manager to halt a program or background process. Other supporting processes continue to run after ending a process they support.

end process tree Option in Task Manager to halt a program or background process and all of its supporting processes.

end task Process of forcibly exiting a program or application, initiated using Task Manager in Windows or Activity Monitor in macOS.

end-user acceptance Change management step that entails educating and training users about what has changed and how to use any new systems, devices, or features.

end-user license agreement See EULA.

Enhanced 911 (E911) Improves 911 service for cellular phones by using GPS and cellular network triangulation to locate the device and dispatch emergency responders.

entry control roster Document for recording who enters and leaves a building.

environment variables System data such as the date and time, currently logged-in users, running operating system version, and more. Scripts and programs on a system often use these variables to tailor their behavior to the system’s capabilities and configuration.

environmental control Practice of protecting computing equipment from environmental damage by taking measures such as air conditioning, proper ventilation, air filtration, temperature monitoring, and humidity monitoring.

equipment rack A metal structure used in equipment rooms to secure network hardware devices and patch panels. Most racks are 19 inches wide. Devices designed to fit in such a rack use a height measurement called units, or simply U.

erase lamp Component inside laser printers that uses light to make the coating of the photosensitive drum conductive.

Error checking Windows graphical tool that scans and fixes hard drive problems. Often referred to by the name of the executable, chkdsk, or Check Disk. The macOS equivalent is the Disk Utility, and Linux offers a command-line tool called fsck.

error correction code See ECC.

eSATA Serial ATA-based connector for external hard drives and optical drives.

escalate Process used when person assigned to repair a problem is not able to get the job done, such as sending the problem to someone with more expertise.

ESD mat See antistatic mat.

ESD strap See antistatic wrist strap.

establish a plan of action to resolve the problem and implement the solution After establishing and testing a theory about a particular problem, techs solve the problem. (Step 4 of 6 in the CompTIA troubleshooting methodology.)

establish a theory of probable cause (question the obvious) After identifying a problem, techs question the obvious to determine what might be the source of the problem. (Step 2 of 6 in the CompTIA troubleshooting methodology.)

Ethernet Name coined by Xerox for the first standard of network cabling and protocols that define everything necessary to get data from one computer to another. Since its inception, Ethernet as a hardware protocol has gone through hundreds of improvements and even forms the basis of wireless networking signals.

Ethernet over Power (EoP) Uses a building’s existing electrical network for Ethernet. Requires specialized bridges between the Ethernet network and power outlets.

Ethic of Reciprocity Golden Rule: Do unto others as you would have them do unto you.

EULA (end-user license agreement) Agreement that accompanies a piece of software, to which the user must agree before using the software. Outlines the terms of use for the software and also lists any actions on the part of the user that violate the agreement.

Event Viewer (eventvwr.msc) Utility made available in Windows as an MMC snap-in that enables users to monitor and audit various system events, including network bandwidth usage and CPU utilization.

evil twin Substitute wireless access point configured to look the same as the real one in order to gather information from users who accidentally connect to it.

exFAT A Microsoft-proprietary file system that breaks the 4-GB file-size barrier, supporting files up to 16 exabytes (EB) and a theoretical partition limit of 64 zettabytes (ZB). Envisioned for use with flash media devices with a capacity exceeding 2 TB.

expansion slots Connectors on a motherboard that enable users to add optional components to a system. See also PCIe.

ext4 (Fourth Extended File System) File system used by most Linux distributions.

extended partition Type of nonbootable hard disk partition. May only have one extended partition per disk. Purpose is to divide a large disk into smaller partitions, each with a separate drive letter.

external enclosure Casing that encloses an external hard drive.

external speaker Portable device that can substantially improve on the audio output of a mobile device or portable computer. Typically connects via Bluetooth or a regular headphone jack.

facial recognition Technology that enables use of facial features to unlock a mobile device or personal computer.

factory recovery partition See recovery partition.

factory reset Returns a device’s software to how it left the factory by removing all user-installed data, programs, and customizations.

FAT (file allocation table) Hidden table that records how files on a hard disk are stored in distinct clusters. The address of the first cluster of a file is stored in the directory file. The FAT entry for the first cluster is the address of the second cluster used to store that file. In the entry for the second cluster for that file is the address for the third cluster, and so on until the final cluster, which gets a special end-of-file marker. There are two FATs, mirror images of each other, in case one is destroyed or damaged. Also refers to the 16-bit file allocation table when used by Windows 2000 and later NT-based operating systems.

FAT32 File allocation table that uses 32 bits to address and index clusters. Commonly used with USB flash-media drives and versions of Windows prior to XP.

fiber optic cable High-speed cable for transmitting data, made of high-purity glass sealed within an opaque tube. Much faster than conventional copper wire such as coaxial cable. Most common connectors include ST, SC, and LC.

file A named collection of any form of data that is stored beyond the time of execution of a single job. A file may contain program instructions or data, which may be numerical, textual, or graphical information.

File Explorer A tool in Windows that enables users to browse files and folders.

file extension Two, three, four, five, or more letters that follow a filename and identify the type of file (file format). Common file extensions are .zip, .exe, .doc, .java, and .xhtml.

file format How information is encoded in a file. Two primary types are binary (pictures) and ASCII (text), but within those are many formats, such as BMP and GIF for pictures. Commonly represented by a suffix (the file extension) at the end of the filename; for example, .txt for a text file or .exe for an executable.

File History Control Panel applet introduced in Windows 8 for backing up personal files and folders.

file permission Specifies what degree of access the system should grant a user or group to a particular file.

file server Computer designated to store software, courseware, administrative tools, and other data on a LAN or WAN. It “serves” this information to other computers via the network when users enter their personal access codes.

file system Scheme that directs how an OS stores and retrieves data on and off a drive; FAT32 and NTFS are both file systems. Used interchangeably with the term “data structure.”

File Transfer Protocol See FTP.

file-level backup Manually or automatically copying individual files or folders to one or more backup locations.

filename Name assigned to a file when the file is first written on a disk. Every file on a disk within the same folder must have a unique name. Filenames can contain any character (including spaces), except the following: / : * ? “ < > |

fileshare A server set up to share documents and other files with other users on a network.

find Linux command used to locate files in the filesystem.

Finder macOS’s file and folder browser.

fingerprint lock Type of biometric device that enables a user to unlock a mobile device using a fingerprint.

fingerprint scanner Scanner that reads the unique pattern of a person’s fingerprint to authenticate them. Used primarily to unlock devices like smartphones and some laptops.

firewall Device that restricts traffic between a local network and the Internet.

firmware Embedded programs or code stored on a ROM chip. Generally OS-independent, thus allowing devices to operate in a wide variety of circumstances without direct OS support. The system BIOS is firmware.

firmware update Process by which the BIOS of a motherboard can be updated to reflect patched bugs and added features. Performed usually through CMOS, though some motherboard manufacturers provide a Windows program for performing a firmware update.

flash ROM ROM technology that can be electrically reprogrammed while still in the PC. Overwhelmingly the most common storage medium of BIOS in computers today, as it can be upgraded without a need to open the computer on most systems.

flux capacitor A rectangular-shaped compartment with three flashing Geissler-style tubes arranged in a “Y” configuration that makes time travel possible.

folder permission Specifies what degree of access the system should grant a user or group to a particular folder.

force stop Terminate an Android app and all associated background processes. More extreme than simply closing the app, which may leave background processes running.

form factor Standard for the physical organization of motherboard components and motherboard size. Most common form factors are ATX, microATX, and Mini-ITX.

format Command-line tool used to format a storage device.

formatting The process of preparing a partition to store files by creating a file system to organize the blocks and creating a root directory.

fragmentation Occurs when files and directories get jumbled on a fixed disk and are no longer contiguous. Can significantly slow down hard drive access times and can be repaired in Windows by using Optimize Drives. See also defragmentation.

frame A data unit transferred across a network. Frames consist of several parts, such as the sending and receiving MAC addresses, the data being sent, and the frame check sequence.

freeware Software that is distributed for free, with no license fee.

FRU (field replaceable unit) Any part of a PC that is considered to be replaceable “in the field,” i.e., a customer location. There is no official list of FRUs—it is usually a matter of policy by the repair center.

FTP (File Transfer Protocol) Rules that enable two computers to talk to one another during a file transfer. Protocol used when you transfer a file from one computer to another across the Internet. FTP uses port numbers 20 and 21.

F-type connector Common coax connector secured with a screw connector.

full device encryption Enhances mobile device security by encrypting the device’s internal storage.

full format Format process that tests every sector to mark out the unusable ones in the file allocation table (FAT). See formatting.

full-duplex Any device that can send and receive data simultaneously.

Full-Speed USB USB standard that runs at 12 Mbps. Also known as USB 1.1.

fully qualified domain name (FQDN) A complete, bottom-to-top label of a DNS host going from the specific host to the top-level domain that holds it and all of the intervening domain layers, each layer being separated by a dot. FQDNs are entered into browser bars and other utilities in formats like mail.totalseminars.com.

Function (FN) key Special key on many laptops that enables some keys to perform a third duty.

Gaming (Windows Settings) Windows Settings category that contains options to optimize and modify gaming experiences.

GDDR5 Fifth generation of graphical DDR RAM found on high-performance video cards.

General Data Protection Regulation (GDPR) European Union law that defines a broad set of rights and protections of personal information for citizens of the EU.

general protection fault (GPF) Error code usually seen when separate active programs conflict on resources or data. Can cause an application to crash.

geofencing Using mobile device features to detect when the device enters or exits a defined area.

geotracking Feature in cellular phones that enables cell phone companies and government agencies to use the ID or MAC address to pinpoint where a phone is at any given time.

gestures Specific motions the user performs on a touchscreen, such as pinching or swiping, that have a special meaning to the app being used.

giga Prefix for the quantity 1,073,741,824 (2³⁰) or for 1 billion. One gigabyte would be 1,073,741,824 bytes, except with hard drive labeling, where it means 1 billion bytes. One gigahertz is 1 billion hertz.

Global Positioning System (GPS) Technology that enables a mobile device to determine where you are on a map.

global user account Login information and associated settings maintained at a location accessible by any computer, irrespective of location or local account configuration.

globally unique identifier (GUID) partition table (GPT) Partitioning scheme that enables you to create more than four primary partitions without needing to use dynamic disks.

Google Play Google’s app and media store for Android devices.

Google Workspace Google’s suite of productivity tools and applications. Can be synchronized across multiple devices to enable more efficient workflow.

gpresult Windows command for listing group policies applied to a user.

GPS See Global Positioning System.

GPU (graphics processing unit) Specialized processor that helps the CPU by taking over all of the 3-D rendering duties.

gpupdate Windows command for making immediate group policy changes in an individual system.

graphical user interface (GUI) See GUI.

grep Linux command to search through text files or command outputs to find specific information or to filter out unneeded information.

group Collection of user accounts that share the same access capabilities.

group policy Means of easily controlling the settings of multiple network clients with policies such as setting minimum password length or preventing Registry edits.

Group Policy Editor (gpedit.msc) MMC snap-in used to change or modify group policy in Windows.

GSM (Global System for Mobile Communications) Wireless data standard for mobile devices.

guest An operating system running inside a virtual machine.

guest account Very limited built-in account type for Windows; a member of the Guests group.

Guests group User group that enables someone without an account to use a system. See group.

GUI (graphical user interface) Interface that enables user to interact with computer graphically, by using a mouse or other pointing device to manipulate icons that represent programs or documents, instead of using only text as in early interfaces. Pronounced “gooey.”

half-duplex Transmission mode where a device can either send or receive, but not do both at once.

hang Occurs when a computer or program stops responding to keyboard commands or other input; a computer or program in such a state is said to be “hung.”

hang time Number of seconds a too-often-hung computer is airborne after you have thrown it out a second-story window.

hard drive See HDD.

hard reset For mobile devices, another term for a factory reset. Don’t confuse this with a hard reboot. See factory reset.

hard token Dedicated device that contains information used as an authentication factor when logging on to a secure site.

hardware Physical computer equipment such as electrical, electronic, magnetic, and mechanical devices. Anything in the computer world that you can hold in your hand. A hard drive is hardware; Microsoft Word is not.

hardware firewall Firewall implemented within networking hardware such as a router. See firewall.

hardware protocol Defines many aspects of a network, from the packet type to the cabling and connectors used. Ethernet is an example of a hardware protocol.

hardware virtualization Processor features that speed up and simplify virtualization. Required for some hypervisors to function. See also hypervisor.

hardware-assisted virtualization Virtualization that makes use of the host machine’s hardware to enable the virtualized software to function.

hash A special value computed from some other value using an irreversible computation. Has many uses in computing, and plays a key role in modern authentication systems. Instead of saving user passwords directly in a database (which would make them a huge target for attackers), well-designed authentication systems compute and save only a (salted) hash of each password. When the user attempts to log in, the system hashes the provided password to see if it matches the saved hash. See also salted hash.

HDD (hard disk drive) Data-recording system using solid disks of magnetic material turning at high speeds to store and retrieve programs and data in a computer.

HDMI (High-Definition Multimedia Interface) Single multimedia connection that includes both high-definition video and audio. Used to connect a computer to LCDs, projectors, and VR headsets.

heat dope See thermal paste.

heat sink A specially designed hunk of metal such as aluminum or copper that conducts heat away from a CPU or other heat-producing component and out into fins that transfer the heat to circulating air. When used to cool a CPU, a heat sink is typically paired with a fan assembly to improve its performance.

hex (hexadecimal) Base-16 numbering system using ten digits (0 through 9) and six letters (A through F). In the computer world, shorthand way to write binary numbers by substituting one hex digit for a four-digit binary number (e.g., hex 9 = binary 1001).

hibernate Power management setting in which all data from RAM is written to the hard drive before the system goes into sleep mode. Upon waking up, all information is retrieved from the hard drive and returned to RAM. Also called suspend to disk.

hidden attribute File attribute that, when used, does not allow the dir command to show a file.

hierarchical directory tree Method by which Windows organizes files into a series of folders, called directories, under the root directory. See also root directory.

high availability A trait of systems that indicates an emphasis on reliable operations with minimal or no downtime.

High Dynamic Range (HDR) Video technology that increases the bandwidth of display colors and light intensity above standard dynamic range.

high-level formatting Format that sets up a file system on a drive.

Hi-Speed USB USB standard that runs at 480 Mbps. Also referred to as USB 2.0.

horizontal cabling Cabling that connects the equipment room to the work areas.

host (networking) On a TCP/IP network, a single device that has an IP address—any device (usually a computer) that can be the source or destination of a data packet. Also, in virtualization, a computer running one or more virtual operating systems.

host (virtualization) The system running (or hosting) a virtual machine.

host ID The address of a TCP/IP device such as a computer, printer, camera, or other device.

hostname Windows command for displaying the name of a computer.

hotspot A mobile device that broadcasts a small Wi-Fi network to share its mobile data network connection with nearby Wi-Fi devices. Often a standalone device, though many cellular phones and data-connected tablets can be set up to act as hotspots.

hot-swappable Any hardware that may be attached to or removed from a PC without interrupting the PC’s normal processing.

hot-swapping Replacing a bad drive in a RAID array without needing to reboot or power down.

HTML (Hypertext Markup Language) ASCII-based, script-like language for creating hypertext documents such as those on the World Wide Web.

HTTP (Hypertext Transfer Protocol) Extremely fast protocol used for network file transfers in the WWW environment. Uses port 80.

HTTPS (HTTP over Secure Sockets Layer) Secure form of HTTP used commonly for Internet business transactions or any time when a secure connection is required. Uses port 443.

hub Electronic device that sits at the center of a star bus topology network, providing a common point for the connection of network devices. Hubs repeat all information out to all ports and have been replaced by switches, although the term “hub” is still commonly used. A USB hub shares a single USB connection and its bandwidth among connected devices.

hybrid A network topology that combines features from multiple other topologies, such as the star bus topology.

hybrid cloud A combination of cloud resources from more than one of the three cloud types (community, private, and public).

Hyper-Threading Intel CPU feature (generically called simultaneous multithreading) that enables a CPU to run more than one thread at once.

hypervisor Software that enables a single computer to run multiple operating systems simultaneously.

I/O (input/output) General term for reading and writing data to a computer. “Input” includes data entered from a keyboard, identified by a pointing device (such as a mouse), or loaded from a disk. “Output” includes writing information to a disk, viewing it on a monitor, or printing it to a printer.

IaaS See Infrastructure as a Service.

iCloud Apple cloud-based storage. iCloud enables a user to back up all iPhone or iPad data and makes that data accessible from anywhere. This includes any media purchased through iTunes as well as calendars, contacts, reminders, and so forth.

ID badge Small card or document for confirming the identity of its holder and what access they should be granted. May use built-in authentication tools such as RFID or smart card to function as a “something you have” authentication factor.

IDE (Integrated Drive Electronics) PC specification for small- to medium-sized hard drives in which the controlling electronics for the drive are part of the drive itself, speeding up transfer rates and requiring only a simple adapter (or “paddle”) connection on a motherboard. IDE only supported two drives per system of no more than 504 MB each and has been completely supplanted by Enhanced IDE. EIDE supports four drives of over 8 GB each and more than doubles the transfer rate. The more common name for PATA drives.

identify the problem To question the user and find out what has been changed recently or is no longer working properly. (Step 1 of 6 in the CompTIA troubleshooting methodology.)

IEC-320 connector Connects the cable supplying AC power from a wall outlet into the power supply.

IEEE (Institute of Electronic and Electrical Engineers) Leading standards-setting group in the United States.

IEEE 802.11 Wireless Ethernet standard more commonly known as Wi-Fi.

image deployment Operating system installation that uses a complete image of a hard drive as an installation media. Helpful when installing an operating system on a large number of identical PCs.

image file Bit-by-bit image of data to be burned on optical media or flash drive—from one file to an entire disk—stored as a single file on a hard drive. Particularly handy when copying from CD to CD or DVD to DVD.

image-level backup Backing up a complete volume, including any OS, boot files, applications, and data it contains.

IMAP4 (Internet Message Access Protocol version 4) An alternative to POP3 that retrieves e-mail from an e-mail server; IMAP uses TCP port 143.

IMEI (International Mobile Equipment Identity) A 15-digit number used to uniquely identify a mobile device, typically a smartphone or other device that connects to a cellular network.

impedance Amount of resistance to an electrical signal on a wire. Relative measure of the amount of data a cable can handle.

impersonation A social engineering attack in which a person pretends to be someone else in order to gain access to confidential data or to launch attacks against a computer network.

incident report Record of the details of an accident, including what happened and where it happened.

incident reporting Process of reporting gathered data about a system or problem to supervisors. Creates a record of work accomplished and may help identify patterns. Often documented on an incident report form.

Infrastructure as a Service (IaaS) Cloud-hosted provider of virtualized servers and networks.

inheritance NTFS feature that passes on the same permissions in any subfolders/files resident in the original folder.

in-place upgrade See upgrade installation.

insider threat Threat to an organization that originates from within. An insider threat can be malicious or accidental, but either way, it introduces some type of risk to safety, data, and the business.

installation media (drivers) Optical media or drive (such as a USB flash drive) that holds all the necessary device driver files for a specific device such as a printer, scanner, or motherboard.

installation media (operating systems) Optical media or drive (such as a USB flash drive) that holds all the necessary files for installing an operating system or an application (program).

integrated GPU GPU integrated with the motherboard or processor, in contrast to GPUs on separate graphics cards. This typically lowers power consumption, saves space, reduces heat, and may speed up communication with the GPU.

Intel One of the two major CPU manufacturers and the original creator of the x86 CPU architecture. Competes directly with AMD in desktop, laptop, and server processors.

interface Means by which a user interacts with a piece of software.

Internet of Things (IoT) Everyday home objects that incorporate computing and networked features to enable enhanced functionality. Smart home devices, home security systems, and even refrigerators can be part of the Internet of Things.

Internet service provider (ISP) Company that provides access to the Internet, usually for money.

interrupt/interruption Suspension of a process, such as the execution of a computer program, caused by an event external to the computer and performed in such a way that the process can be resumed. Events of this kind include sensors monitoring laboratory equipment or a user pressing an interrupt key.

intrusion detection system (IDS) Application that inspects packets, looking for active intrusions. Functions inside the network, looking for threats a firewall might miss, such as viruses, illegal logon attempts, and other well-known attacks. May also discover threats from inside the network, such as a vulnerability scanner run by a rogue employee.

intrusion prevention system (IPS) Application similar to an intrusion detection system (IDS), except that it sits directly in the flow of network traffic. This enables it to stop ongoing attacks itself, but may also slow down the network and be a single point of failure.

inventory management A process for protecting devices and equipment by tagging them with barcodes or asset tags and keeping track of these tagged devices.

inverter Device used to convert DC current into AC. Commonly used in older laptops and flatbed scanners with CCFLs.

iOS The operating system of Apple iPhones.

IoT See Internet of Things.

ip Command-line utility for Linux servers and workstations that displays the current TCP/IP configuration of the machine. Similar to ipconfig in Windows.

IP address Numeric address of a computer connected to the Internet. An IPv4 address is made up of four octets of 8-bit binary numbers (32 bits total) translated into their shorthand numeric values. An IPv6 address is 128 bits long. The IP address can be broken down into a network ID and a host ID. Also called Internet address.

iPadOS The operating system of Apple’s iPad tablets.

ipconfig Command-line utility for Windows servers and workstations that displays the current TCP/IP configuration of the machine. Similar to ip in Linux.

IPS (in-plane switching) Display technology that replaces the older twisted nematic (TN) panels for more accurate colors and a wider viewing angle.

IPsec (Internet Protocol security) Microsoft’s encryption method of choice for networks consisting of multiple networks linked by a private connection, providing transparent encryption between the server and the client.

IPv4 (Internet Protocol version 4) Internet standard protocol that provides a common layer over dissimilar networks; used to move packets among host computers and through gateways if necessary. Part of the TCP/IP protocol suite. Uses the dotted-decimal format—x.x.x.x. Each x represents an 8-bit binary number, or 0–255. Here’s an example: 192.168.4.1.

IPv6 (Internet Protocol version 6) Protocol in which addresses consist of eight sets of four hexadecimal numbers, each number being a value between 0000 and ffff, using a colon to separate the numbers. Here’s an example: fedc:ba98:7654:3210:0800:200c:00cf:1234.

ISO file Complete copy (or image) of a storage media device, typically used for optical discs. ISO image files typically have a file extension of .iso.

ISP See Internet service provider.

ITX (Information Technology eXtended) A family of motherboard form factors. Mini-ITX is the largest and the most popular of the ITX form factors but is still quite small.

jack (physical connection) Part of a connector into which a plug is inserted. Also referred to as a port.

jailbreaking Process for circumventing the security restrictions present on an iOS device.

jitter Network issue in which packets are delayed by variable lengths of time, leading to poor performance.

joule Unit of energy describing (in this book) how much energy a surge suppressor can handle before it fails.

jumper Pair of small pins that can be shorted with a shunt to configure many aspects of PCs. Often used in configurations that are rarely changed.

Keep my files Windows Recovery Environment option in Windows 10 that rebuilds the OS but preserves user files, settings, and Microsoft Store applications (while deleting all other applications on the system).

Kerberos Authentication encryption developed by MIT to enable multiple brands of servers to authenticate multiple brands of clients.

kernel Core portion of program that resides in memory and performs the most essential operating system tasks.

kernel panic The Linux/macOS equivalent of the Windows BSoD. An error from which the OS can’t recover without a reboot. See also Blue Screen of Death.

key fob Generically, just about anything attached to a key ring that isn’t a key. Some security tools, such as hardware security tokens and RFID authentication devices, are commonly designed as key fobs.

Keychain A macOS password management and storage service that saves passwords for computer and non-computer environments. Also, the iCloud Keychain adds synchronization among any macOS and iOS devices connected to the Internet for a user account.

keylogger Software, usually malware, that copies, saves, and sometimes uploads all keystrokes and other inputs on a computer. Keyloggers are used to gather information such as passwords, Web sites visited, and other activities performed on a computer.

kill Command in UNIX shells (such as Bash) and in PowerShell that terminates an indicated process.

KVM (keyboard, video, mouse) switch Hardware device that enables multiple computers to be viewed and controlled by a single mouse, keyboard, and screen.

LAN (local area network) Group of computers connected via cabling, radio, or infrared that uses this connectivity to share resources such as printers and mass storage.

laser Single-wavelength, in-phase light source that is sometimes strapped to the head of sharks by bad guys. Note to henchmen: Lasers should never be used with sea bass, no matter how ill-tempered they might be. They should, however, be used in optical disc technology, laser-based projectors, single-mode fiber optic cables, and/or laser printers.

latency Amount of delay before a device may respond to a request; most commonly used in reference to RAM.

launcher An Android app that serves as the device’s desktop, often with more extensive customization features than launchers provided by Google or the device maker.

LBA See logical block addressing.

LC See Lucent connector.

LCD (liquid crystal display) Type of display commonly used on portable computers. LCDs have also replaced CRTs as the display of choice for desktop computer users. LCDs use liquid crystals and electricity to produce images on the screen.

lease A temporary IP address assignment to a device on the network from a pool of available addresses.

LED (light-emitting diode) Solid-state device that vibrates at luminous frequencies when current is applied.

Level 1 (L1) cache First RAM cache accessed by the CPU, which stores only the absolutely most accessed programming and data used by currently running threads. Always the smallest and fastest cache on the CPU.

Level 2 (L2) cache Second RAM cache accessed by the CPU. Much larger and often slower than the L1 cache, and accessed only if the requested program/data is not in the L1 cache.

Level 3 (L3) cache Third RAM cache accessed by the CPU. Much larger and slower than the L1 and L2 caches and accessed only if the requested program/data is not in the L2 cache.

LGA (land grid array) Arrangement of a large number of pins extending from the CPU socket to corresponding contact points on the bottom of the CPU.

Libraries Feature in Windows that aggregates folders from multiple locations and places them in a single, easy-to-find spot in File Explorer. Default libraries in Windows include Documents, Music, Pictures, and Videos.

Lightning An 8-pin connector, proprietary to Apple, that can be inserted without regard to orientation. Used to connect mobile devices to a power or data source.

Lightweight Directory Access Protocol (LDAP) Protocol used for obtaining directory information over a network. Uses port 389.

Li-Ion (Lithium-Ion) Battery commonly used in portable computing devices. Li-Ion batteries don’t suffer from the memory effects of Nickel-Cadmium (Ni-Cd) batteries and provide much more power for a greater length of time.

link light An LED on NICs, hubs, and switches that lights up to show good connection between the devices.

link-local address IPv6 address a computer gives itself when it first boots. IPv6’s equivalent to IPv4’s APIPA address.

Linux Open-source UNIX-clone operating system.

liquid cooling A method of cooling a PC that works by running some liquid—usually water—through a metal block that sits on top of the CPU, absorbing heat. The liquid gets heated by the block, runs out of the block and into something that cools the liquid, and is then pumped through the block again.

load balancer A device that spreads network traffic across multiple servers in order to improve availability of resources.

local area network See LAN.

Local Security Policy Windows tool used to set local security policies on an individual system.

local share File sharing server that only shares with local devices on a LAN.

local user account List of usernames and their associated passwords with access to a system, contained in an encrypted database.

local username Username that is stored on the device, rather than on an Active Directory domain controller.

Local Users and Groups (lusrmgr.msc) Tool enabling creation and changing of group memberships and accounts for users.

location data Information provided by a mobile device’s GPS; used for mapping functions as well as for location-aware services, such as finding nearby restaurants or receiving coupons for nearby shops.

locator application Application designed to enable the user of a mobile device or laptop to locate the device in the event that it was lost or stolen.

log files Files created in Windows to track the progress of certain processes.

logical block addressing (LBA) Addressing scheme that presents storage chunks on a storage device to the OS as a sequence of blocks beginning with LBA0. This saves the OS from having to deal directly with the details of how storage space is arranged on a hard drive or SSD.

logical drives Sections of an extended partition on a hard drive that are formatted and (usually) assigned a drive letter, each of which is presented to the user as if it were a separate drive.

logical security Security measures focused on denying access to networks, systems, and data.

logon screen First screen of the Windows interface, used to log on to the computer system.

Long Term Evolution (LTE) Fourth-generation cellular network technology supporting theoretical download speeds up to 1 Gbps and upload speeds up to 100 Mbps. Marketed as and now generally accepted as a true 4G technology.

long-range fixed wireless Method of wirelessly connecting networks when it isn’t feasible to run cables. Uses directional antennas and can connect buildings up to several miles away.

loop Control construct used in a script or program to repeat a sequence of instructions when certain conditions are met. For example, a script could use a loop to a set of instructions for resizing an image once for every image file in a directory.

loopback plug Device used during loopback tests to check the female connector on a NIC.

loopback test Special test to confirm a NIC can send and receive data. A full external loopback test requires a loopback plug inserted into the NIC’s port.

ls UNIX equivalent of the dir command, which displays the contents of a directory.

LTE See Long Term Evolution.

Lucent connector (LC) Type of fiber optic connector. See fiber optic cable.

M.2 Type of space-efficient expansion slot common in recent portable computers. Also found on some desktop motherboards. M.2 is available in different configurations to support Wi-Fi cards and SSDs.

Mac Common name for Apple Computers’ flagship operating system, as well as their desktop and laptop computers; Apple calls the current operating system macOS.

MAC (mandatory access control) Authorization method in which the system grants access to resources based on security labels and clearance levels. Less flexible than discretionary access control (DAC), which lets users assign access levels to resources they own. MAC may be used in organizations with very high security needs.

MAC (media access control) address Unique 48-bit address assigned to each network card. IEEE assigns blocks of possible addresses to various NIC manufacturers to help ensure that the address is always unique. The Data Link layer of the OSI model uses MAC addresses to locate machines.

MAC address filtering Method of limiting wireless network access based on the physical, hard-wired address of the wireless NIC of a computing device.

machine language Binary instruction code that is understood by the CPU.

macOS Operating system from Apple that powers its desktop and portable computers. Based on UNIX; most versions of macOS run on Intel/IBM-based hardware, just like Microsoft Windows. The latest versions of macOS also support Apple’s new M1 and M2 ARM-based processors. Before 2016, it was known as OS X. See also Mac.

magnetic hard drives Storage devices that read and write data encoded magnetically onto spinning aluminum platters.

magnetometer A fancy way of saying metal detector.

mail server Networked host or server that provides e-mail service.

maintenance kit Set of commonly replaced printer components provided by many manufacturers.

malware Broadly, software designed to use your computer or device against your wishes. Includes adware, spyware, viruses, ransomware, etc. May be part of seemingly legitimate software or installed by exploiting a vulnerability in the device.

MAM See mobile application management.

man Linux command short for manual. Brings up user manual for a wide variety of other Linux commands and utilities.

MAN (metropolitan area network) 802.11 network that covers a single city.

mandatory access control See MAC (mandatory access control).

man-in-the-middle attack See on-path attack.

mass storage Hard drives, optical discs, removable media drives, etc.

master boot record (MBR) Tiny bit of code that takes control of the boot process from the system BIOS.

Material Safety Data Sheet (MSDS) Standardized form that provides detailed information about potential environmental hazards and proper disposal methods associated with various computing components.

md (mkdir) Command-line tool used to create directories.

MDM See mobile device management.

media access control See MAC (media access control) address.

mega- Prefix that stands for the binary quantity 1,048,576 (2²⁰) or the decimal quantity of 1,000,000. One megabyte is 1,048,576 bytes. Sometimes shortened to Meg, as in “my video card has 8 Megs of video RAM.” One megahertz, however, is a million hertz.

memory Device or medium for temporary storage of programs and data during program execution. Synonymous with storage, although it most frequently refers to the internal storage of a computer that can be directly addressed by operating instructions. A computer’s temporary storage capacity is measured in kilobytes (KB), megabytes (MB), or gigabytes (GB) of RAM (random-access memory). Long-term data storage on hard drives and solid-state drives is also measured in megabytes, gigabytes, and terabytes.

mesh topology Network topology where each computer has a dedicated line to every other computer, most often used in wireless networks.

metered utilization Fee charged by cloud service providers on the basis of how much of a resource was used. Fees may be based on things like access time, bandwidth used, bytes uploaded or downloaded, CPU usage, and other resource usage metrics.

metropolitan area network See MAN.

MFA See multifactor authentication.

MFD See multifunction device.

MFT (master file table) Enhanced file allocation table used by NTFS. See also FAT.

micro Secure Digital (microSD) The smallest form factor of the SD flash memory standard. Often used in mobile devices.

microATX (µATX) Variation of the ATX form factor, which uses the ATX power supply. MicroATX motherboards are generally smaller than their ATX counterparts but retain all the same functionality.

microprocessor “Brain” of a computer. Primary computer chip that determines relative speed and capabilities of the computer. Also called the central processing unit (CPU).

Microsoft 365 Microsoft’s subscription suite of productivity apps; includes Word, Teams, Outlook, SharePoint, PowerPoint, and numerous other applications used in homes and businesses around the world.

Microsoft Management Console (MMC) A shell program in Windows that holds individual utilities called snap-ins, designed for administration and troubleshooting. The MMC enables an administrator to customize management tools by picking and choosing from a list of snap-ins. Available snap-ins include Device Manager, Event Viewer, Local Users and Groups, and Computer Management.

Microsoft Remote Assistance (MSRA) Feature of Windows that enables users to give anyone control of his or her desktop over the Internet.

microUSB USB connector commonly found on a variety of devices including Android phones. Slowly being replaced by USB Type-C connectors (especially in Android phones).

migration Moving users from one operating system or hard drive to another. Particularly common when upgrading operating systems or migrating from a mechanical hard drive (HDD) to a solid-state drive (SSD).

MIMO (multiple in/multiple out) Feature of 802.11n devices that enables the simultaneous connection of up to four antennas, greatly increasing throughput. 802.11ac also uses Multiuser MIMO (MU-MIMO), which gives a WAP the capability to broadcast to multiple users simultaneously.

mini connector One type of power connector from a PC power supply unit. Supplies 5 and 12 volts to peripherals.

Mini-ITX The largest and the most popular of the three ITX form factors. At a miniscule 6.7 by 6.7 inches, Mini-ITX competes with microATX and proprietary small form factor (SFF) motherboards.

miniUSB Smaller USB connector often found on digital cameras.

mirror set A type of mirrored volume created with RAID 1. See also mirroring.

mirror space Storage Space that mirrors files across two or more drives, like RAID 1 or RAID 10. See Storage Spaces.

mirrored volume Volume that is mirrored on another volume. See also mirroring.

mirroring Reading and writing data at the same time to two drives for fault tolerance purposes. Considered RAID level 1. Also called drive mirroring.

Mission Control A feature of macOS that enables switching between open applications, windows, and more.

mkdir See md.

MMC See Microsoft Management Console.

mobile application management (MAM) Enables IT to make and enforce policies regarding appropriate and safe application use on business devices and premises as well as allowing them to push updates and make changes to specific applications.

mobile device Small, highly portable computing device with tightly integrated components designed to be worn or carried by the user. Includes smartphones, tablets, and wearable devices.

mobile device management (MDM) A formalized structure that enables an organization to account for all the different types of devices used to process, store, transmit, and receive organizational data.

mobile device management (MDM) policies Technical controls that govern how mobile devices are used as tools in the workplace.

mobile hotspot See hotspot.

Molex connector Computer power connector used by optical drives, hard drives, and case fans. Keyed to prevent it from being inserted into a power port improperly.

monitor Screen that displays data from a PC. Typically a flat-panel display, such as an LCD.

motherboard Flat piece of circuit board that resides inside your computer case and has a number of connectors on it. Every device in a PC connects directly or indirectly to the motherboard, including CPU, RAM, hard drives, optical drives, keyboard, mouse, and video cards.

motherboard book Valuable resource when installing a new motherboard. Normally lists all the specifications about a motherboard, including the type of memory and type of CPU usable with the motherboard.

move Command-line tool used to move a file from one location to another.

mSATA Standardized smaller SATA form factor for use in portable devices.

MSDS See Material Safety Data Sheet.

msinfo32 (System Information) Provides information about hardware resources, components, and the software environment.

multiboot installation OS installation in which multiple operating systems are installed on a single machine.

multicore processing Using two or more execution cores on one CPU die to divide up work independently of the OS.

multifactor authentication (MFA) Authentication schema requiring more than one unique authentication factor. The factors are knowledge, possession, inherence, location, and temporal. For example, a password (knowledge factor) and a fingerprint (inherence factor) is a basic form of multifactor authentication.

multifunction device (MFD) Single device that consolidates functions from more than one document-handling device, such as a printer, copier, scanner, or fax machine.

multimeter Device used to measure voltage, amperage, and resistance.

multimode Type of fiber optic cabling capable of transmitting multiple light signals at the same time using different reflection angles within the cable core. Signals tend to degrade over distance, limiting multimode cable to short distances. See fiber optic cable.

multiple Desktops A GUI feature that enables a computer to have more than one Desktop, each with its own icons and background. macOS supports multiple Desktops with Spaces. Most Linux distros use multiple Desktops, often called workspaces. Microsoft introduced the feature with Windows 10.

multitasking Process of running multiple programs or tasks on the same computer at the same time.

multitouch Input method on many smartphones and tablets that enables you to perform gestures (actions with multiple fingers) to do all sorts of fun things, such as using two fingers to scroll or swipe to another screen or desktop.

Multiuser MIMO (MU-MIMO) New version of MIMO included in 802.11ac that enables a WAP to broadcast to multiple users simultaneously.

mv The move command in Linux and macOS.

NAT (Network Address Translation) A means of translating a system’s IP address into another IP address before sending it out to a larger network. NAT manifests itself by a NAT program that runs on a system or a router. A network using NAT provides the systems on the network with private IP addresses. The system running the NAT software has two interfaces: one connected to the network and the other connected to the larger network. The NAT program takes packets from the client systems bound for the larger network and translates their internal private IP addresses to its own public IP address, enabling many systems to share a single IP address.

native resolution Resolution on an LCD monitor that matches the physical pixels on the screen.

near-field communication See NFC.

near-field scanner Enables mobile devices to use near-field communication to read things like barcodes and bank cards.

net Command-line utility in Windows that enables users to view and change a whole host of network settings and information.

net use Subcommand of the Windows net command that enables a user to connect, disconnect, and view information about existing connections to network resources.

net user Subcommand of the Windows net command that enables a user to create, delete, and change user accounts.

NetBIOS (Network Basic Input/Output System) Protocol that operates at the Session layer of the OSI seven-layer model. This protocol creates and manages connections based on the names of the computers involved. Uses TCP ports 137 and 139 and UDP ports 137 and 138.

netstat Command-line tool in Windows and Linux to identify inbound and outbound TCP/IP connections with the host.

network Collection of two or more computers interconnected by telephone lines, coaxial cables, satellite links, radio, and/or some other communication technique that communicate with one another for a common purpose.

Network Interface in File Explorer that displays networked computers and other devices, such as network printers.

Network & Internet (Windows Settings) Windows Settings category that contains options and settings relating to networks and Internet connectivity, including checking connection status, network sharing, and VPN settings.

network attached storage (NAS) A device that attaches to a network for the sole purpose of storing and sharing files.

network connection A method for connecting two or more computers together. See also network.

network documentation A road map to an organization’s network configuration and topology to guide techs who need to change or repair the network.

network ID Logical number that identifies the network on which a device or machine exists. This number exists in TCP/IP and other network protocol suites.

network interface card (or controller) See NIC.

network protocol Software that takes the incoming data received by the network card, keeps it organized, sends it to the application that needs it, and then takes outgoing data from the application and hands it to the NIC to be sent out over the network.

network topology diagram A map of how everything in an organization’s network (including switches, routers, WAPs, services, and workstations) connects. May indicate connection types, speed, technologies, and so on.

NFC (near-field communication) Mobile technology that enables short-range wireless communication between mobile devices. Now used for mobile payment technology such as Apple Pay and Google Pay.

NIC (network interface card or controller) Expansion card or motherboard interface that enables a PC to connect to a network via a network cable. A wireless NIC enables connection via radio waves rather than a physical cable. Also commonly called a wireless card or Wi-Fi card.

nit Value used to measure the brightness of an LCD display. A typical LCD display has a brightness of between 100 and 400 nits.

nonvolatile Describes storage that retains data even if power is removed; typically refers to a ROM or flash ROM chip, but also could be applied to hard drives, optical media, and other storage devices.

notification area Windows GUI feature that contains icons representing background processes, the system clock, and volume control. Located by default at the right edge of the Windows taskbar. Many users call this area the system tray.

nslookup Command-line program in Windows used to determine exactly what information the DNS server is providing about a specific host name.

NTFS (New Technology File System) Robust and secure file system introduced by Microsoft with Windows NT. NTFS provides an amazing array of configuration options for user access and security. Users can be granted access to data on a file-by-file basis. NTFS enables object-level security, long filename support, compression, and encryption.

NTFS permissions Restrictions that determine the amount of access given to a particular user on a system using NTFS.

NVIDIA Corporation One of the foremost manufacturers of graphics cards and chipsets.

NVMe (Non-Volatile Memory Express) SSD technology that supports a communication connection between the operating system and the SSD directly through a PCIe bus lane, reducing latency and taking full advantage of the speeds of high-end SSDs. NVMe SSDs come in a few formats, such as an add-on expansion card, though most commonly in M.2 format. NVMe drives are a lot more expensive currently than other SSDs, but offer much higher speeds. NVMe drives use SATAe.

object System component that is given a set of characteristics and can be managed by the operating system as a single entity.

ohm(s) A unit of measurement of electronic resistance; used to measure cable’s impedance.

OLED (organic light-emitting diode) Display technology where an organic compound provides the light for the screen, thus eliminating the need for a backlight or inverter. Used in high-end TVs and small devices such as smart watches, smartphones, and VR headsets.

on-path attack Attacker serves as an intermediary between two systems, enabling the attacker to observe, redirect, or even alter messages passing in either direction. Also commonly known as a man-in-the-middle (MITM) attack.

operating system (OS) Series of programs and code that creates an interface so users can interact with a system’s hardware; for example, Windows, macOS, and Linux.

optical disc/media Types of data discs (such as DVDs, CDs, BDs, etc.) that are read by a laser.

optical drive Drive used to read/write to optical discs, such as CDs or DVDs.

optical network terminal (ONT) Works like a modem, but for fiber optic networks. Enables your networked devices to communicate with an Internet service provider.

optimization Changes made to a system to improve its performance.

OS See operating system.

overclocking To run a CPU or video processor faster than its rated speed.

overloaded network A mobile network that, often due to a large public event, emergency, or network equipment failure, is unable to keep up with user demand. Users may have good signal quality but be unable to access data, text, or voice services.

owner In both NTFS and UNIX permissions, usually the user that created a given file or folder, although both systems support changing ownership to another user.

Ownership permission Special NTFS permissions granted to the account that owns a file or folder. Owners can do anything they want to the files and folders they own, including changing their permissions.

PaaS See Platform as a Service.

packet Basic component of communication over a network. Group of bits of fixed maximum size and well-defined format that is switched and transmitted as a single entity through a network. Contains source and destination addresses, data, and control information. Packets are included within (and are not the same thing as) a frame.

page file See virtual memory.

PAN (personal area network) Small wireless network created with Bluetooth technology and intended to link computers and other peripheral devices.

parallel execution When a multicore CPU processes more than one thread.

parity RAM Earliest form of error-detecting RAM; stored an extra bit (called the parity bit) to verify the data.

parity space Storage Space that adds resiliency similar to RAID 5 or RAID 6. See Storage Spaces.

partition Section of the storage area of a hard disk. Created during initial preparation of the hard disk, before the disk is formatted. Also called a volume.

partition boot sector Sector of a partition that stores information important to its partition, such as the location of the OS boot files. Responsible for loading the OS on a partition.

partition table Table located in the boot sector of a hard drive that lists every partition on the disk that contains a valid operating system.

partitioning Electronically subdividing a physical drive into one or more units called partitions (or volumes).

passcode lock Mobile device security feature that requires you enter a series of letters, numbers, or motion patterns to unlock the mobile device each time you press the power button.

password Key used to verify a user’s identity on a secure computer or network.

password manager Software that uses strong encryption to protect stored passwords, removing the need to remember all the various and complex passwords a person uses for their various online accounts.

patch Small piece of software released by a software manufacturer to correct a flaw or problem with a particular piece of software. Also called an update.

patch cables Short (typically two- to five-foot) UTP cables that connect patch panels to a switch or router.

patch management Process of keeping software updated in a safe, timely fashion.

patch panel A panel containing a row of female connectors (ports) that terminate the horizontal cabling in the equipment room. Patch panels facilitate cabling organization and provide protection to horizontal cabling.

path Route the operating system must follow to find an executable program stored in a subfolder.

pattern lock Mobile device screen lock that requires the user to swipe a certain pattern in order to be authenticated and unlock the device.

PCI (Peripheral Component Interconnect) Design architecture for the expansion bus on the computer motherboard that enabled system components to be added to the computer. Used parallel communication and was replaced by PCIe.

PCI DSS (Payment Card Industry Data Security Standard) A standard that sets common rules for systems that accept, process, transmit, or store credit/debit card payments. Often referred to as just PCI.

PCIe (PCI Express) Serialized successor to PCI and AGP that uses the concept of individual data paths called lanes. May use any number of lanes, although a single lane (×1) and 16 lanes (×16) are the most common on motherboards.

PCIe 6/8-pin power connector Connector on some power supplies for powering a dedicated graphics card.

peer-to-peer network Network in which each machine can act as both a client and a server.

Performance Tab in Task Manager that tracks PC performance, including CPU usage, available physical memory, size of the disk cache, and other details about memory and processes.

Performance Monitor (perfmon.msc) Windows tool for tracking system resources over time.

Performance Options Tool that enables users to configure CPU, RAM, and virtual memory settings.

peripheral Any device that connects to the system unit.

permission propagation Describes what happens to permissions on an object, such as a file or folder, when you move or copy it.

personal area network See PAN.

Personalization (Windows Settings) Windows Settings category that enables users to configure preferences such as the background picture for both the desktop and lock screen, colors of interface elements, themes, which elements show on the Start screen, and so on.

personally identifiable information (PII) Any data that can lead back to a specific individual.

PGA (pin grid array) Arrangement of a large number of pins extending from the bottom of the CPU package into corresponding holes in the CPU socket.

Phillips-head screwdriver Most important part of a PC tech’s toolkit.

phishing A social engineering attack intended to get people to give their usernames, passwords, or other security information by pretending to be someone else electronically.

physical security Security measures intended to protect facilities and systems from physical threats like unauthorized entry, burglary, or other threats.

ping Command-line utility used to send a “ping” message to another computer, which can be used to verify another system is on the network, spot potential DNS issues, identify latency problems, and so on.

Pinwheel of Death See Spinning Pinwheel of Death.

pipe Command-line operator that uses the | symbol to “pipe” output from one command to another, instead of printing it to the screen.

pipeline Processing methodology where multiple calculations take place simultaneously by being broken into a series of steps. Often used in CPUs and video processors.

pixel (picture element) In computer graphics, smallest element of a display space that can be independently assigned color or intensity.

pixels per inch (PPI) Density of pixels on a display or a light sensor; the higher the density, the greater the resolution.

PKI (public key infrastructure) Authentication schema where public keys are exchanged between all parties using digital certificates, enabling secure communication over public networks.

Platform as a Service (PaaS) Cloud-based virtual server(s) combined with a platform that gives programmers the tools needed to deploy, administer, and maintain a Web application.

plenum Space in the ceiling, walls, and floor where special plenum-grade (fire-retardant) network cables can be run out of sight.

plug and play (PnP) Combination of smart PCs, smart devices, and smart operating systems that automatically configure all necessary system resources and ports when you install a new peripheral device.

policies Control permission to perform a given action, such as accessing a command prompt, installing software, or logging on at a certain time of day. Contrast with true permissions, which control access to specific resources.

POP3 (Post Office Protocol 3) One of the two protocols that receive e-mail from SMTP servers. POP3 uses TCP port 110. While historically most e-mail clients used this protocol, the IMAP4 e-mail protocol is now more common.

port (networking) In networking, the number used to identify the requested service (such as SMTP or FTP) when connecting to a TCP/IP host. Examples include application protocol ports such as 80 (HTTP), 443, (HTTPS), 21 (FTP), 23 (Telnet), 25 (SMTP), 110 (POP3), 143 (IMAP), and 3389 (RDP).

port (physical connection) Part of a connector into which a plug is inserted. Physical ports are also referred to as jacks.

port forwarding Router configuration that enables outside traffic to reach a particular node on a secured network, such as a server. Port forwarding translates the IP address and port number used to reach the network by a remote client into the IP address and port number used by a particular node on the network.

port replicator Device that plugs into a USB port or Thunderbolt port and offers common PC ports, such as VGA, HDMI, USB, network, and so on. Plugging a laptop into a port replicator can instantly connect the computer to nonportable components such as a printer, scanner, monitor, or full-sized keyboard. Port replicators are typically used at home or in the office with the nonportable equipment already connected.

portable battery recharger Device containing a rechargeable battery that can be used to charge other devices, typically over USB, when no outlets are available.

POST (power-on self-test) Basic diagnostic routine completed by a system at the beginning of the boot process to make sure a display adapter and the system’s memory are installed. In the event that there is some problem with the hardware, you’ll generally hear some combination of beeps indicating where the problem is; consult the motherboard book. It then searches for an operating system. If it finds one, it hands over control of the machine to the OS.

POST card Device installed into a motherboard expansion slot that assists in troubleshooting boot problems by providing a two-digit code indicating the stop of the boot process where the problem is occurring.

potential The amount of electrical energy stored in an object.

power conditioning Ensuring and adjusting incoming AC wall power to as close to standard as possible. Most UPS devices provide power conditioning.

power management Cooperation between hardware, BIOS, and OS to reduce power consumption.

Power Options Windows Control Panel applet that enables better control over power use by customizing a Balanced, Power saver, or High-performance power plan.

Power over Ethernet (PoE) Technology that provides power and data transmission through a single network cable.

power plan Preconfigured profiles (such as Balanced, High performance, and Power saver) in the Power Options applet that modify a Windows system’s behavior to adjust power consumption.

power supply unit (PSU) Provides the electrical power for a PC. Converts standard AC power into various voltages of DC electricity in a PC.

Power Users group After Administrator/Administrators, the second most powerful account and group type in Windows. Power users have differing capabilities in different versions of Windows.

power-saving modes Special power modes that limit or modify device functionality in order to prolong battery life. May take steps such as disabling communications, reducing processor speed, limiting programs, and dimming the screen.

PowerShell See Windows PowerShell.

preboot execution environment (PXE) Technology that enables a PC to boot without any local storage by retrieving an OS from a server over a network.

primary partition Partition on a Windows hard drive that can store a bootable operating system.

principle of least privilege Accounts should have permission to access only the resources they need and no more.

print server Server, computer, or standalone network device that shares access to a printer over a network.

printed circuit board (PCB) Copper etched onto a nonconductive material and then coated with some sort of epoxy for strength.

Privacy (Windows Settings) Windows Settings category that contains options related to privacy.

private cloud Cloud network built and maintained by or explicitly for a specific company or organization. Often on-site, but may be provided by a third party. While a public cloud network often requires more expertise and costs more, especially up front, it also enables greater customization and security.

PRL (Preferred Roaming List) A list that is occasionally and automatically updated to a phone’s firmware by the carrier so that the phone will be configured with a particular carrier’s networks and frequencies, in a priority order, that it should search for when it can’t locate its home carrier network.

Processes Tab in Task Manager that lists all running processes on a system. Frequently a handy tool for ending buggy or unresponsive processes.

product key Code used during installation to verify legitimacy of the software.

profile (MDM) A collection of mobile device management (MDM) configuration and security settings that an administrator has created in order to apply those settings to particular categories of users or devices.

profile (network) Collection of information necessary to automatically connect to a network, stored by the network’s SSID. Enables mobile and portable devices to easily use many networks.

profile (user) Describes a Windows user account’s customized environment, including Desktop preferences, color schemes, shortcuts, and so on.

program/programming Series of binary electronic commands sent to a CPU to get work done.

Programs and Features Windows Control Panel applet; enables uninstalling or changing program options and altering Windows features.

projector Device for projecting video images from PCs or other video sources, usually for audience presentations.

prompt A character or message provided by an operating system or program to indicate that it is ready to accept input.

proprietary Technology unique to a particular vendor.

proprietary crash screen A screen, differing between operating systems, that indicates an NMI. See also BSoD and Spinning Pinwheel of Death.

protected health information (PHI) Personally identifiable information that relates to a person’s health status, medical records, and healthcare services they have received.

protocol Agreement that governs the procedures used to exchange information between cooperating entities. Usually includes how much information is to be sent, how often it is to be sent, how to recover from transmission errors, and who is to receive the information.

proxy server Software that enables multiple connections to the Internet to go through one protected computer. Common security feature in the corporate world. Applications that want to access Internet resources send requests to the proxy server instead of trying to access the Internet directly, which both protects the client computers and enables the network administrator to monitor and restrict Internet access.

ps Linux command for listing all processes running on the computer.

public cloud Cloud network built and maintained by a large company for use by any individual or company who wants to create an account and start paying for services.

Public folder Folder that all users can access and share with all other users on the system or network.

public key infrastructure See PKI.

punchdown block Connector used to connect UTP cable to a patch panel. Wires are attached to the block using a punchdown tool.

punchdown tool A specialized tool for connecting UTP wires to a punchdown block.

PVC (polyvinyl chloride) Material used to make the plastic protective sheathing around many basic network cables. Produces noxious fumes when burned.

pwd Linux command that displays the user’s current path.

QR scanner An application or device capable of scanning and interpreting QR codes.

quad-channel architecture Feature similar to dual-channel RAM, but making use of four sticks of RAM instead of two.

Quality of Service (QoS) Router feature used to prioritize access to network resources. Ensures certain users, applications, or services are prioritized when there isn’t enough bandwidth to go around by limiting the bandwidth for certain types of data based on application protocol, the IP address of a computer, and all sorts of other features.

quick format High-level formatting that creates just the file allocation table and a blank root directory. See also formatting.

radio frequency (RF) The part of the electromagnetic spectrum used for radio communication.

radio frequency identification (RFID) Wireless technology that uses small tags containing small amounts of digital information and readers capable of accessing it. Passive RFID tags operate by harvesting some of the power a scanner or reader emits, enabling a vast array of applications. Common uses such as tracking inventory, identifying lost pets, contactless payments, authentication, and wireless door locks are just scratching the surface. See also asset tag, ID badge, key fob, and smart card.

RAID (redundant array of independent [or inexpensive] disks) Method for creating a fault-tolerant storage system. RAID uses multiple hard drives in various configurations to offer differing levels of speed/data redundancy.

RAID 0 Uses byte-level striping and provides no fault tolerance.

RAID 0+1 A RAID 0 configuration created by combining two RAID 1 arrays. Provides both speed and redundancy, but requires at least four disks.

RAID 1 Uses mirroring or duplexing for increased data redundancy.

RAID 5 Uses block-level and parity data striping. Requires three or more drives.

RAID 5 volume (dynamic disks) A software-based RAID 5 volume made up of three or more dynamic disks with equal-sized unallocated space. Created with Windows Disk Management.

RAID 6 Disk striping with extra parity. Like RAID 5, but with more parity data. Requires four or more drives, but you can lose up to two drives at once and your data is still protected.

RAID 10 The opposite of RAID 0+1, two mirrored RAID 0 configurations. Provides both speed and redundancy and also requires four disks.

RAM (random access memory) Memory that can be accessed at random—that is, memory that you can write to or read from without touching the preceding address. This term is often used to mean a computer’s main memory.

ransomware A nasty form of malware that encrypts data or drives on the infected system and demands payment, often within a limited timeframe, in exchange for the keys to decrypt the data.

rapid elasticity Characteristic of cloud computing that enables cloud consumers to add or remove capacity quickly. Because cloud servers are powered by virtual machines, customers can start or shut down new instances of VMs or move the VMs to more powerful hardware.

rd (rmdir) Command-line tool used to remove directories.

read-only attribute File attribute that does not allow a file to be altered or modified. Helpful when protecting system files that should not be edited.

real-time clock (RTC) Device within the CMOS memory chip that provides date and time information to the computer and operating system.

recent apps Interface for viewing a list of recently used apps on a mobile device.

reciprocity See Ethic of Reciprocity.

recovery partition Small hidden partition on a system’s primary hard drive with a factory-fresh OS image to recover and reinstall from.

Recycle Bin Location to which files are moved when they are deleted from a modern Windows system. To permanently remove files from a system, they must be emptied from the Recycle Bin.

refresh rate Time required for a monitor to redraw the whole screen.

regedit.exe Program used to edit the Windows Registry.

registration (printing) Describes how accurately the printer lays down each color layer that makes up a page or image. Poor registration can result in muddled colors or a fringe of pure color around a shape or image. Printers usually have a routine (which may mention calibration, alignment, or registration) for detecting and fixing alignment issues.

registration (product) Usually optional process that identifies the legal owner/user of the product to the supplier.

Registry Complex binary file used to store configuration data about a particular Windows system. To edit the Registry, users can use the Registry Editor or use regedit.

Registry Editor (regedit.exe) Program used to edit the Windows Registry.

remediation Repairing damage caused by a virus.

remnant Potentially recoverable data on a hard drive that remains despite formatting or deleting.

Remote Assistance See Microsoft Remote Assistance.

remote desktop Generically, the process of using one system to access the desktop or graphical user interface (GUI) of a remote system.

Remote Desktop Connection Windows tool used to form a remote desktop connection and graphically access the GUI of a remote system.

Remote Desktop Protocol (RDP) Protocol used for Microsoft’s Remote Desktop tool. Uses port 3389.

remote network installation A common method of OS installation where the source files are placed in a shared directory on a network server. Then, a tech who needs to install a new OS can boot the computer, connect to the source location on the network, and start the installation from there.

remotely wipe The ability to remotely delete user data from a mobile device that has been lost or stolen.

removable media Any storage on a computer that can be easily removed. For example, optical discs, flash drives, or memory cards.

Remove everything Windows Recovery Environment option in Windows 10 that deletes all apps, programs, user files, and user settings, resulting in a fresh installation of Windows. Use as a last resort when troubleshooting (and back up data first).

replication When a virus makes copies of itself, often by injecting itself into other executables. See malware and virus.

reset to factory default Another term for a factory reset.

resistance Difficulty in making electricity flow through a material, measured in ohms.

resistor Any material or device that impedes the flow of electrons. Antistatic wrist straps and mats use tiny resistors to prevent a static charge from racing through the device.

resolution Measurement for monitors and printers expressed in horizontal and vertical dots or pixels. Higher resolutions provide sharper details and thus display better-looking images.

Resource Monitor (resmon.exe) Windows utility that displays detailed performance information about a computer’s CPU, memory, disk, and network activity.

resources Data and services such as files, folders, drives, printers, connections, and so on.

response rate The amount of time it takes for all the sub-pixels on an LCD panel to change from one state to another. This change is measured in one of two ways: black-to-white (BtW) measures how long it takes the pixels to go from pure black to pure white and back again, and gray-to-gray (GtG) measures how long it takes the pixels to go from one gray state to another.

restore point A snapshot of a computer’s configuration at a specific point in time, created by the System Restore utility and used to restore a malfunctioning system. See also System Restore.

retina scanner Biometric security device that authenticates an individual by comparing retinal scans. Rarer in the real world than in media such as movies or video games.

RFI (radio frequency interference) Another form of electrical interference caused by radio wave–emitting devices, such as cell phones, wireless network cards, and microwave ovens.

RG-6 Coaxial cabling used for cable television. It has a 75-ohm impedance and uses an F-type connector.

RG-59 Coaxial cable used for cable television, cable modems, and broadcast TV; thinner than RG-6, which makes it suitable for shorter patch cables.

riser card Special adapter card, usually inserted into a special slot on a motherboard, that changes the orientation of expansion cards relative to the motherboard. Riser cards are used extensively in slimline computers to keep total depth and height of the system to a minimum. Sometimes called a daughter board.

risk analysis A detailed assessment of any problems that could result from a change.

RJ (registered jack) connector UTP cable connector, used for both telephone and network connections. RJ-11 is a connector for four-wire UTP; usually found in telephone connections. RJ-45 is a connector for eight-wire UTP; usually found in network connections.

RJ-11 See RJ (registered jack) connector.

RJ-45 See RJ (registered jack) connector.

rm Linux command for deleting files.

rmdir See rd (rmdir).

roaming When a mobile device connects to a network not owned by its home carrier.

robocopy Powerful command-line utility for copying files and directories, even over a network.

rogue anti-malware Free application that claims to be anti-malware but is actually malware.

ROM (read-only memory) Generic term for nonvolatile memory that can be read from but not written to. This means that code and data stored in ROM cannot be corrupted by accidental erasure. Additionally, ROM retains its data when power is removed, which makes it the perfect medium for storing BIOS data or information such as scientific constants.

root directory Directory that contains all other directories. Also known as root folder.

root keys Five main categories in the Windows Registry:

rooting Process for circumventing the security restrictions and gaining access to the root user account on an Android device.

rootkit Program that takes advantage of very low-level functionality to gain privileged system access and hide itself from all but the most aggressive anti-malware tools. Can strike operating systems, hypervisors, and even device firmware.

router Device connecting separate networks; forwards a packet from one network to another based on the network address for the protocol being used. For example, an IP router looks only at the IP network number. Routers operate at Layer 3 (Network) of the OSI seven-layer model.

RSA token Random-number generator used along with a username and password to enhance security.

RU (rack-mounted unit) Height measurement used for rack-mounted equipment. An RU is 1.75 inches. A device that fits in a 1.75-inch space is called a 1RU; a device designed for a 3.5-inch space is a 2RU; and a device that goes into a 7-inch space is called a 4RU.

run (networking) A single piece of installed horizontal cabling.

Run as administrator Method of running a Windows program with elevated privileges, disabling protections that normally limit a program’s ability to damage the system.

SaaS See Software as a Service.

Safe Mode Important diagnostic boot mode for Windows that runs only very basic drivers and turns off virtual memory.

safety goggles Protective glasses that keep stuff out of your eyes.

salted hash See salting.

salting The process of protecting password hashes from being easily reversed with a rainbow table by adding additional values to each password before hashing and storing it.

SAN See storage area network.

sandbox Virtualized computer used as a restricted environment to safely run untrusted applications or test new applications without posing risk to an actual system or network.

SAS (Serial Attached SCSI) Fast, robust storage interface based on the SCSI command set. Also supports SATA drives. Used mainly in servers and storage arrays.

SATA (serial ATA) Serialized version of the ATA standard that offers many advantages over PATA (parallel ATA) technology, including thinner cabling, keyed connectors, and lower power requirements.

SATA 3.2 Another term for SATAe. See SATA Express.

SATA Express (SATAe) Version of SATA that ties capable drives directly into the PCI Express bus on motherboards. Each lane of PCIe 3.0 is capable of handling up to 8 Gbps of data throughput. A SATAe drive grabbing two lanes, therefore, could move a whopping 16 Gbps through the bus.

SATA power connector 15-pin, L-shaped connector used by SATA devices that support the hot-swappable feature.

SC See subscriber connector.

SCADA See supervisory control and data acquisition.

scope of the change Defines who and what the change will affect. May include an inventory of systems to change, people involved, time required, and estimated cost.

screen lock Mobile device and Windows feature that locks the screen until some form of authentication challenge is passed.

screen orientation Describes whether a mobile device screen is in portrait or landscape mode and the device settings that govern when the orientation may change. When the screen orientation setting is in automatic mode, the user interface (UI) will switch between portrait and landscape modes based on the device’s orientation in physical space.

screened subnet A lightly protected or unprotected subnet network positioned between an outer firewall and an organization’s highly protected internal network. Screened subnets are used mainly to host public address servers (such as Web servers). Also commonly known as a demilitarized zone (DMZ).

script Set of text instructions that tells a computer a series of commands to execute in a repeatable fashion.

scripting language Set of commands, syntax, variables, and format for scripts to be used in a specific computer environment. For example, bash is a scripting language often used in the Bash shell, which is common on UNIX environments.

SCSI (small computer system interface) Long-lived storage drive technology once common in the server market. Has been through many iterations. Today, the SCSI command set lives on in Serial Attached SCSI (SAS) hard drives. See also SAS.

SDRAM (synchronous DRAM) Dynamic RAM that is synchronous, or tied to the system clock. This type of RAM is used in all modern systems.

Search (box or field) Location on the Windows 10 taskbar next to the Start button where users can input text and see relevant suggestions (for settings, programs, files, and popular Web searches).

sector Magnetically preset storage areas on traditional magnetic hard drives. On older hard drives, a sector held 512 bytes of data; modern drives use 4096-byte Advanced Format (AF) sectors.

Secure Boot UEFI feature that secures the boot process by requiring properly signed software. This includes boot software and software that supports specific, essential components.

Secure Shell (SSH) Terminal emulation program similar to Telnet, except that the entire connection is encrypted. Uses port 22.

Secure Sockets Layer (SSL) Security protocol used by a browser to connect to secure Web sites. Replaced by Transport Layer Security (TLS).

security token Device that stores some unique information that a user carries with them. May contain digital certificates, passwords, biometric data, or RSA tokens.

segment The connection between a computer and a switch.

self-grounding A less-than-ideal method for ridding yourself of static electricity by touching a metal object such as a computer case.

Serial Attached SCSI See SAS.

serial presence detect (SPD) Information stored on a RAM chip that describes the speed, capacity, and other aspects of the RAM chip.

server Computer that shares its resources, such as printers and files, with other computers on a network. Example: network file system server that shares its disk space with a workstation that does not have a disk drive of its own.

Server Message Block (SMB) Windows’ network file and print sharing protocol, though every major OS now supports it. Protocol of choice for LAN file servers. Uses TCP port 445 and UDP ports 137, 138, and 139.

service A process that runs in the background of a PC but displays no icons anywhere. You can view a list of services in the Windows Task Manager. Also, a program stored in a ROM chip.

service menu Hidden device menu containing tools for technicians servicing the device. May contain diagnostics, reports, or interfaces for changing otherwise inaccessible settings.

service pack Collection of software patches released at one time by a software manufacturer.

Services Tab in Windows Task Manager that lists all running services on a system. See also service.

Settings app Windows app that combines a huge number of otherwise disparate utilities, apps, and tools traditionally spread out all over your computer into one fairly unified, handy interface.

sfc (System File Checker) Command-prompt program (sfc.exe) that scans, detects, and restores Windows system files, folders, and paths.

SFTP (Secure FTP) Secure version of the File Transfer Protocol (FTP) that uses port 22. See also FTP.

shared resources Consolidating resources from many systems into a smaller number of more powerful systems, reducing power, maintenance, and hardware costs.

shell Tool that interprets command-line input, also known as the command-line interpreter.

shielded twisted pair See STP.

shoulder surfing Social engineering attack where a malicious actor obtains credentials or other sensitive information by watching someone use a computer or device, often over their shoulder.

shunt Tiny connector of metal enclosed in plastic that creates an electrical connection between two posts of a jumper. Also known as a jumper block.

shutdown Windows and Linux command-line tool for shutting down the computer.

SID (security identifier) Unique identifier for every PC that most techs change when cloning.

side-by-side apps Windows feature for quickly pinning an app to the left or right half of a screen.

signature (malware) Code pattern of a known virus or malware that antivirus/anti-malware software uses to detect malware.

signature file See definition file.

signed driver A driver designed specifically to work with Windows that has been tested and certified by Microsoft to work stably with Windows.

Simple Mail Transport Protocol See SMTP.

Simple Network Management Protocol See SNMP.

simple space Storage Space that just pools storage space, like just a bunch of disks (JBOD). See Storage Spaces.

simple volume Volume created when setting up dynamic disks. Acts like a primary partition on a dynamic disk.

single sign-on (SSO) Process that uses an account or credentials for a popular service (such as a Google Account) to sign on or authenticate with other services.

single-factor authentication A less-secure authentication process using only one of the authentication factors. See also multifactor authentication.

single-mode fiber optic cabling Type of fiber optic cabling that uses laser light to transmit at very high rates over long distances. Still fairly rare. See also fiber optic cable.

single-sided RAM Has chips on only one side, as opposed to double-sided RAM.

sleep mode Power management setting in which all data from RAM is preserved by powering down much of the computer but maintaining power to RAM, or by writing the contents of RAM to the mass storage drive before the system goes into a reduced-power mode. Upon waking up, the information is retrieved from the HDD or SSD and returned to RAM if necessary; the system continues where it left off.

slot covers Metal plates that cover up unused expansion slots on the back of a PC. Useful in maintaining proper airflow through a computer case.

S.M.A.R.T. (Self-Monitoring, Analysis, and Reporting Technology) Monitoring system built into hard drives that tracks errors and error conditions within the drive.

smart card Hardware authentication involving a credit card–sized card with circuitry that can be used to identify the bearer of that card.

smart card reader Device that scans the smart card chip, such as those in ID badges. Common applications include enhancing the security of doors or laptops.

smartphone A cell phone enhanced to do things formerly reserved for desktop and laptop computers, such as Web browsing, document viewing, and media consumption.

SMTP (Simple Mail Transport Protocol) Main protocol used to send electronic mail on the Internet. Uses port 25.

snap-ins Utilities that can be used with the Microsoft Management Console.

snapshot Virtualization feature that enables you to save an extra copy of the virtual machine as it is exactly at the moment the snapshot is taken.

SNMP (Simple Network Management Protocol) A set of standards for communication with devices connected to a TCP/IP network. Examples of these devices include routers, hubs, and switches. Uses ports 161 and 162.

social engineering Using or manipulating people inside the networking environment to gain access to that network from the outside.

SO-DIMM (small-outline DIMM) Memory used in portable PCs because of its small size.

soft power Characteristic of ATX motherboards, which can use software to turn the PC on and off. The physical manifestation of soft power is the power switch. Instead of the thick power cord used in AT systems, an ATX power switch is little more than a pair of small wires leading to the motherboard.

soft reset The equivalent of a reboot or restart for a mobile device. An important troubleshooting step because it clears running programs from memory and restarts the operating system. Some portable devices that closely resemble mobile devices may also use soft resets.

soft token Programming (usually running on a general computing device such as a smartphone or portable computer) that enables the device to serve as an authentication factor when logging on to a secure resource.

software Single group of programs designed to do a particular job; always stored on mass storage devices.

Software as a Service (SaaS) Cloud-based service to store, distribute, and update programs and applications. The SaaS model provides access to necessary applications wherever you have an Internet connection, often without having to carry data with you or regularly update software. At the enterprise level, the subscription model of many SaaS providers makes it easier to budget and keep hundreds or thousands of computers up to date.

software firewall Firewall implemented in software running on servers or workstations. See firewall.

software-defined networking (SDN) Networking method that uses software tools to control network administration and traffic. SDN allows for the programming of the network to improve efficiency.

solid core A cable that uses a single solid (not hollow or stranded) wire to transmit signals.

solid-state drive See SSD.

spam Unsolicited e-mails from both legitimate businesses and scammers that account for a huge percentage of traffic on the Internet.

spam gateway Software used to filter incoming e-mail to prevent spam.

spanned volume Volume that uses space on multiple dynamic disks.

SPD See serial presence detect.

speaker Device that outputs sound by using a magnetically driven diaphragm.

spear phishing Dangerous targeted phishing attack on a group or individual that carefully uses details from the target’s life to increase the odds they’ll take the bait.

spindle speed Fixed speed in revolutions per minute (RPM) at which a given HDD’s platters spin. The two most common speeds are 5400 and 7200 RPM; higher-performance drives (far less common) run at 10,000 and 15,000 RPM. Also called rotational speed.

Spinning Pinwheel of Death (SPoD) A spinning rainbow wheel (sometimes referred to as a “beach ball”) that serves as the macOS indicator that an application isn’t responding and may be busy or frozen.

spoofing Pretending to be someone or something else by placing false information into packets. Commonly spoofed data include a source MAC address or IP address, e-mail address, Web address, or username. Generally a useful tool for enhancing or advancing other attacks, such as social engineering or spear phishing.

spyware Software that runs in the background of a user’s PC, sending information about browsing habits back to the company that installed it onto the system.

SQL attack See Structured Query Language (SQL) attack.

SRAM (static RAM) Very high-speed RAM built into CPUs that reduces wait states by preloading as many instructions as possible and keeping copies of already run instructions and data in case the CPU needs to work on them again.

SSD (solid-state drive) Data storage device that uses flash memory to store data.

SSH See Secure Shell.

SSID (service set identifier) Parameter used to define a wireless network; otherwise known as the network name.

SSL See Secure Sockets Layer.

ST See straight tip.

standard user account User account in Windows that has limited access to a system. Part of the Users group. Accounts of this type cannot alter system files, cannot install new programs, and cannot edit some settings by using the Control Panel without supplying an administrator password.

standby See sleep mode.

standoffs Small mechanical separators that screw into a computer case. A motherboard is then placed on top of the standoffs, and small screws are used to secure it to the standoffs.

star bus topology A hybrid network topology where the computers all connect to a central bus—a switch—and have a layout resembling a star.

Start button Clickable element on the Windows taskbar that enables access to the Start menu.

Start menu Menu that can be accessed by clicking the Start button on the Windows taskbar. Enables you to see all programs loaded on the system and to start them.

Start screen Windows 10 version of the Start menu, which functions as a combination of the traditional Start menu and Windows 8/8.1 modern UI.

Startup Repair A one-stop, do-it-all troubleshooting option that performs a number of boot repairs automatically.

Stateful Packet Inspection (SPI) Used by hardware firewalls to inspect each incoming packet individually for purposes such as blocking traffic that isn’t in response to outgoing requests.

static IP address Manually set IP address that will not change.

storage area network (SAN) Storage setup in which, rather than using internal drives, a device accesses a separate block of hard drives on a network separate from the normal network, reading them logically as one drive.

storage pool One or more physical drives grouped into a single Storage Space.

Storage Spaces In Windows, a software RAID solution that enables users to group multiple drives into a single storage pool.

STP (shielded twisted pair) Cabling for networks, composed of pairs of wires twisted around each other at specific intervals. Twists serve to reduce interference (also called crosstalk)—the more twists, the less interference. Cable has metallic shielding to protect the wires from external interference.

straight tip (ST) Type of fiber optic connector. See fiber optic cable.

stranded core A cable that uses a bundle of tiny wire filaments to transmit signals. Stranded core is not quite as good a conductor as solid core, but it will stand up to substantial handling without breaking.

streaming media Broadcast of data that is played on your computer and immediately discarded.

string In programming and scripting, a non-numeric sequence of alphanumeric data.

stripe set Two or more drives in a group that are used for a striped volume.

striped volume RAID 0 volumes. Data is spread across two drives for increased speed.

strong password Password containing at least eight characters, including letters, numbers, and punctuation symbols.

structured cabling ANSI/TIA standards that define methods of organizing the cables in a network for ease of repair and replacement.

Structured Query Language (SQL) A language that enables a program to interact with a database using various commands and queries.

Structured Query Language (SQL) attack An attack that occurs when an attacker enters SQL commands into an input field on a Web app in order to gain access to data or an entire database that the attacker isn’t supposed to see.

su Older Linux command for gaining root access.

subfolder A folder located inside another folder.

subnet mask Value used in TCP/IP settings to divide the IP address of a host into its component parts: network ID and host ID.

sub-pixels Tiny liquid crystal molecules arranged in rows and columns between polarizing filters used in LCDs. A pixel is composed of a red, a green, and a blue sub-pixel.

subscriber connector (SC) Type of fiber optic connector. See fiber optic cable.

su/sudo Linux command for gaining root access.

SuperSpeed USB A fast form of USB, with speeds up to 5 Gbps. Also called USB 3.0, USB 3.1 Gen 1, or USB 3.2 Gen 1.

SuperSpeed USB 10 Gbps Updated form of SuperSpeed USB providing speeds up to 10 Gbps. Also called USB 3.1 or USB 3.2 Gen 2.

supervisory control and data acquisition (SCADA) Hardware and software combination used to monitor and control the operational technology used in industrial settings such as public transit systems, power plants, and refineries.

surge suppressor Inexpensive device that protects your computer from voltage spikes.

suspend See sleep mode.

swap file See virtual memory.

swap partition Special partition found on Linux and UNIX systems that behaves like RAM when your system needs more RAM than is installed.

swipe lock Mobile device feature that uses a swipe gesture to unlock the mobile device.

switch Device that filters and forwards traffic based on some criteria. A bridge and a router are both examples of switches. In the command-line interface, a switch is a function that modifies the behavior of a command.

swollen battery A Li-Ion battery that has begun to swell as it fails, often due to manufacturing defects, heat, or overcharging. May also deform the device containing it. It is an explosion and fire risk if it ruptures, so dispose of it quickly and safely.

sync The process of keeping files on mobile devices up to date with the versions on desktop computers or over the Internet via cloud-based services.

Sync Center Windows Control Panel applet where network files marked as Always available offline may be viewed.

synchronize See sync.

syntax (command) The proper way to write a command-line command so that it functions and does what it’s supposed to do.

System (Windows Settings) The proverbial “junk drawer” category of Windows Settings categories. System contains everything from display options, to sound settings, to notifications settings.

system BIOS Primary set of BIOS stored on a flash ROM chip on the motherboard. Defines the BIOS for all the assumed hardware on the motherboard, such as keyboard controller, basic video, and RAM.

system bus speed Speed at which the CPU and the rest of the PC operates; set by the system crystal.

System Configuration (msconfig.exe) Windows tool to edit and troubleshoot operating system and program startup processes and services.

system crystal Crystal that provides the speed signals for the CPU and the rest of the system.

system fan Any fan controlled by the motherboard but not directly attached to the CPU.

System File Checker See sfc.

System Information tool See msinfo32.

system lockout Protects against attempts to brute-force a lock screen or login system by locking the user out until they perform some more thorough authentication process. Occurs when too many consecutive login attempts fail.

system on a chip (SoC) Single silicon die containing a CPU, GPU, and other important support logic.

System Preferences macOS tool containing many administrative functions.

System Protection Tab in Windows System Properties dialog box that enables you to configure how and when the system will create restore points and provides easy access to existing restore points via System Restore.

system resources In classic terms, the I/O addresses, IRQs, DMA channels, and memory addresses. Also refers to other computer essentials such as hard drive space, system RAM, and processor speed.

System Restore Utility in Windows that enables you to return your PC to a recent working configuration when something goes wrong. System Restore enables you to select a restore point and then returns the computer’s system settings to the way they were at that restore point—all without affecting your personal files or e-mail.

system ROM Flash ROM chip that stores the system BIOS.

system setup utility See CMOS setup program.

system tray See notification area.

system unit Main component of the desktop PC, in which the CPU, RAM, optical drive, hard drive, and power supply reside. All other devices—the keyboard, mouse, and monitor—connect to the system unit.

system/application log errors May indicate the presence of a malware infestation and the scope of its effects.

%SystemRoot% The path where the operating system is installed.

T568A Wiring standard for Ethernet cable.

T568B Wiring standard for Ethernet cable.

tablet A mobile device consisting of a large touchscreen, enabling the user to browse the Web, view media, and even play games.

tailgating Form of infiltration and social engineering that involves following someone else through a door as if you belong in the building.

Take Ownership Special permission allowing users to seize control of a file or folder and potentially prevent others from accessing the file/folder.

Task Manager Windows utility that shows all running programs, including hidden ones, and is accessed by pressing CTRL-SHIFT-ESC. You can use the Task Manager to shut down an unresponsive application that refuses to close normally.

Task Scheduler (taskschd.msc) Windows utility enabling users to set tasks to run automatically at certain times.

taskbar Contains the Start button, Search box, pinned apps, running apps, and the notification area. Located by default at the bottom of the desktop.

taskkill Windows command-line tool for killing running processes.

tasklist Windows command-line tool for listing and managing processes.

TCP See Transmission Control Protocol.

TCP/IP (Transmission Control Protocol/Internet Protocol) Communication protocols developed by the U.S. Department of Defense to enable dissimilar computers to share information over a network. TCP/IP is the primary protocol of most modern networks, including the Internet.

TCP/IP services Services such as HTTP or SSH that run atop TCP/IP.

TDR (time-domain reflectometer) Device for testing network cabling by measuring impedance (which is similar to resistance); any impedance means a bad cable.

tech toolkit Tools a PC tech should never be without, including a Phillips-head screwdriver, a pair of plastic tweezers, a flat-head screwdriver, a hemostat, a star-headed Torx wrench, a parts retriever, and a nut driver or two.

telecommunications room Area where all the cabling from individual computers in a network converges.

Telnet Terminal emulation program for TCP/IP networks that allows one machine to control another as if the user were sitting in front of it. Uses port 23.

tera- Prefix that usually stands for the binary number 1,099,511,627,776 (2⁴⁰). When used for mass storage, it’s often shorthand for 1 trillion bytes.

terminal Dumb device connected to a mainframe or computer network that acts as a point for entry or retrieval of information.

Terminal A command-line tool available in macOS and various Linux distros.

terminal emulation Software that enables a computer to communicate with another computer or network as if the computer were a specific type of hardware terminal.

test the theory to determine the cause Attempt to resolve the issue by either confirming the theory and learning what needs to be done to fix the problem or by not confirming the theory and forming a new one or escalating. (Step 3 of 6 in the CompTIA troubleshooting methodology.)

tethering The act of using a cellular network–connected mobile device as a mobile hotspot.

theory of probable cause One possible reason why something is not working; a guess or hypothesis.

thermal compound See thermal paste.

thermal pad Heat-transferring pad that can be used as an alternative to thermal paste. Typically preapplied to OEM heat sinks supplied with processors and covers for M.2 drives.

thermal paste Paste-like material with very high heat-transfer properties. Applied between the CPU and the cooling device, it ensures the best possible dispersal of heat from the CPU. Also called heat dope or thermal compound.

thermal printer Printer that uses heated printheads to create high-quality images on special or plain paper. Common in retail receipt printers, which use large rolls of thermal paper housed in a feed assembly that automatically draws the thermal receipt paper over the heating element.

thin provisioning Creating a Storage Space that reports a size greater than the actual capacity installed in the computer, with the ability to later add more physical capacity up to the reported size. See also Storage Spaces.

This PC Commonly used interface for Windows Explorer that displays hard drives and devices with removable storage.

thread Smallest logical division of a single program.

throttling Power reduction/thermal control capability allowing CPUs to slow down during low activity or high heat build-up situations.

throw Size of the image a projector displays at a certain distance from the screen.

Thunderbolt An open standards connector interface that is primarily used to connect peripherals to devices, including mobile devices, if they have a corresponding port.

Time & Language (Windows Settings) Windows Settings category that allows you to change the date, time, and language on a Windows system.

Time Machine macOS backup tool that enables you to create full system backups, called local snapshots, and to recover some or all files in the event of a crash; it also enables you to restore deleted files and recover previous versions of files.

TLS See Transport Layer Security.

TN (twisted nematic) Older technology for LCD monitors. TN monitors produce a decent display for a modest price, but they have limited viewing angles and can’t accurately reproduce all the color information sent by the video card.

tone generator See toner.

tone probe See toner.

toner Generic term for two devices used together—a tone generator and a tone probe (locator)—to trace cables by sending an electrical signal along a wire at a particular frequency. The tone probe then emits a sound when it distinguishes that frequency.

topology The way computers connect to each other in a network.

touch interface The primary user interface on modern mobile devices where keys are replaced with tactile interaction.

touch pen Device designed to be used in conjunction with touchscreens to create a drawing or writing experience. Touch pens can be as simple as a plastic stylus, all the way to the advanced Apple Pencil, which uses sensors and a Bluetooth connection to the device to enhance its effectiveness.

touchscreen Monitor with a type of sensing device (a digitizer) across its face that detects the location and duration of contact, usually by a finger or stylus.

traceroute macOS and Linux command-line utility for following the path a packet takes between hosts. The Windows version is named tracert.

tracert Windows command-line utility used to follow the path a packet takes between two hosts. The utility is traceroute in macOS and Linux.

traces Small electrical connections embedded in a circuit board.

trackpad Flat, touch-sensitive pad that serves as a pointing device for most laptops.

transfer rate Rate of data transferred between two devices, especially over the expansion bus.

Transmission Control Protocol (TCP) Connection-oriented protocol used with TCP/IP. See also User Datagram Protocol and TCP/IP.

transmit beamforming Multiple-antenna technology that adjusts the signal when clients are discovered to optimize quality and minimize dead spots. Employed in many 802.11n WAPs and standard in 802.11ac and 802.11ax WAPs.

Transport Layer Security (TLS) Encryption protocol used to securely connect between servers and clients, such as when your Web browser securely connects to Amazon’s servers to make a purchase. Replaces SSL.

triple-channel architecture A chipset feature similar to dual-channel RAM, but making use of three matched sticks of RAM instead of two.

Trojan Program that does something other than what the user who runs the program thinks it will do. Used to disguise malicious code, also known as a Trojan horse.

troubleshooting methodology Steps a technician uses to solve a problem. CompTIA A+ defines six steps: identify the problem; establish a theory of probable cause (question the obvious); test the theory to determine the cause; establish a plan of action to resolve the problem and implement a solution; verify full system functionality and, if applicable, implement preventive measures; and document findings, actions, and outcomes.

Trusted Platform Module (TPM) A hardware platform for the acceleration of cryptographic functions and the secure storage of associated information. BitLocker, for example, requires a TPM chip on the motherboard or equivalent to validate on boot that the computer has not changed. Recent Intel and AMD processors include TPM functions.

trusted root CA A highly respected certificate authority (CA) that has been placed on the lists of trusted authorities built into Web browsers.

trusted source Legitimate app stores run by the major OS vendors such as Apple, Google, Microsoft, and Amazon.

tunneling Creating an encrypted link between two programs on two separate computers.

two-factor authentication Authentication process that provides additional security by requiring two different authentication factors. See also multifactor authentication.

UAC (User Account Control) Windows feature implemented to stop unauthorized changes to Windows. UAC enables standard accounts to do common tasks and provides a permissions dialog box when standard and administrator accounts do certain things that could potentially harm the computer (such as attempt to install a program).

UDP See User Data Protocol.

UEFI (Unified Extensible Firmware Interface) Modern 32- or 64-bit firmware programming interface. Replaced the original 16-bit PC BIOS. UEFI supports large-capacity storage drives, additional features, and a more direct booting process.

unattended installation A type of OS installation where special scripts perform all the OS setup duties without human intervention.

unauthorized access Anytime a person accesses resources in an unauthorized way. This access may or may not be malicious.

UNC (Universal Naming Convention) Describes any shared resource in a network using the convention \<server name><name of shared resource>.

unified threat management (UTM) Providing robust network security by integrating traditional firewalls with many other security services such as IPS, VPN, load balancing, anti-malware, and more.

unpatched system Provides robust network security by integrating traditional firewalls with many other security services such as IPS, VPN, load balancing, anti-malware, and more.

unshielded twisted pair See UTP.

untrusted source Stores or sites where apps can be obtained outside of the legitimate trusted sources run by major vendors. See trusted source.

UPC (Universal Product Code) Barcode used to track inventory.

update See patch.

Update & Security (Windows Settings) Windows Settings category that includes options related to Windows updates and security features, including Windows Defender.

upgrade installation Installation of Windows on top of an earlier installed version, thus inheriting all previous hardware and software settings.

UPS (uninterruptible power supply) Device that supplies continuous clean power to a computer system the whole time the computer is on. Protects against power outages and sags (and corresponding data loss).

URL (uniform resource locator) An address that defines the location of a resource on the Internet. URLs are used most often in conjunction with HTML and the World Wide Web.

USB (universal serial bus) General-purpose serial interconnect for keyboards, printers, joysticks, drives, scanners, and many other devices. Enables hot-swapping of devices.

USB host controller Integrated circuit normally built into the chipset that acts as the interface between the system and every USB device that connects to it.

USB hub Device that extends a single USB connection to two or more USB ports, almost always directly from one of the USB ports connected to the root hub.

USB root hub Part of the host controller that makes the physical connection to the USB ports.

USB thumb drive Flash memory device that has a standard USB connector.

USB Type-C (connector) Reversible USB-type cable that supports up to USB 3.2 with a top speed of 10 Gbps. Quickly becoming the de facto standard port on Android devices. Thunderbolt-enabled USB Type-C ports can reach top speeds of 40 Gbps. See also Thunderbolt.

user account Container that identifies a user to an application, operating system, or network. Includes name, password, username, groups to which the user belongs, and other information based on the user and the OS being used. Usually defines the rights and roles a user plays on a system.

User Accounts Applet in Control Panel that enables you to make changes to local user accounts and gives you access to the Settings app when you opt to add a new account.

User Datagram Protocol (UDP) Connectionless protocol used with TCP/IP. See also Transmission Control Protocol and TCP/IP.

user interface Visual representation of the computer on the monitor that makes sense to the people using the computer, through which the user can interact with the computer. This can be a graphical user interface (GUI) like Windows 10 or a command-line interface (CLI) like Windows PowerShell.

user password Credentials assigned to a login account that does not have administrative capabilities.

user profile Settings that correspond to a specific user account and may follow the user regardless of the computers where they log on. These settings enable the user to have customized environment and security settings.

Users Tab in Task Manager that shows other logged-in users and enables you to log off other users if you have the proper permissions. Also includes information on resources consumed by programs the user is running.

Users folder Windows default location for content specific to each user account on a computer. It is divided into several folders such as Documents, Pictures, Music, and Videos.

Users group List of local users not allowed to edit the Registry or access critical system files, among other things. They can create groups, but can only manage the groups they create.

USMT (User State Migration Tool) Advanced application for file and settings transfer of many users.

Utilities macOS folder that contains tools for performing services on a Mac beyond what’s included in System Preferences, including Activity Monitor and Terminal.

UTP (unshielded twisted pair) Popular type of cabling for telephone and networks, composed of pairs of wires twisted around each other at specific intervals. The twists serve to reduce interference (also called crosstalk). The more twists, the less interference. Unlike shielded twisted pair (STP), UTP cable has no metallic shielding to protect the wires from external interference. 1000BASE-T uses UTP, as do many other networking technologies. UTP is available in a variety of grades, called categories, as follows:

variables In scripting and programming, named labels for some portion of in-memory data. The actions taken by the script or program may change or replace the data in the variable.

verify full system functionality and, if applicable, implement preventive measures Making sure that a problem has been resolved and will not return. (Step 5 of 6 in the CompTIA troubleshooting methodology.)

vertical alignment (VA) Display technology used in mid-range LCD panels. VA refers to how the liquid crystal matrix is arranged within the panel.

VESA mount A screen or display bracket that follows the industry standard—established by the Video Electronics Standards Association (VESA)—which specifies size, location, and type of mounting points.

VGA connector A 15-pin, three-row, D-type VGA monitor connector. Goes by many other names, such as D-shell, D-subminiature connector, DB-15, DE15, and HD15. The oldest and least-capable monitor connection type.

vi Linux and macOS command-line tool for editing text files.

video capture Computer jargon for the recording of video information, such as TV shows or movies.

video card Expansion card that works with the CPU to produce the images displayed on your computer’s display.

video display See monitor.

viewing angle Width (measured from the center to the side of a display) range within which the image can be fully seen.

virtual assistant Voice-activated technology that responds to user requests for information. Virtual assistants can be used to search the Internet, make reminders, do calculations, and launch apps.

virtual desktop infrastructure (VDI) Hosting desktops (Windows, Linux, or macOS) on a server so they can be used in VMs on remote devices. Not to be confused with VDI virtual machine disk images.

virtual machine (VM) A complete environment for a guest operating system to function as though that operating system were installed on its own computer.

virtual memory Portion of the hard drive set aside by an OS to act like RAM when the system needs more RAM than is installed. A file containing this data is typically called a page file in Windows and a swap file in UNIX platforms like Linux and macOS.

Virtual Network Computing (VNC) Protocol enabling remote desktop connections. See also remote desktop.

virus A program that has two jobs: to replicate and to activate. Replication means it copies itself. Activation is when a virus damages a system or data. A virus can’t self-replicate across networks; it needs human action to spread to other drives. See also definition file.

virus shield Passive monitoring of a computer’s activity, checking for viruses only when certain events occur, such as a program execution or file download.

vishing A social engineering attack in which the attacker uses the phone to scam an unsuspecting user out of information that can be used to cause further harm.

VoIP (Voice over Internet Protocol) Collection of protocols that makes voice calls over a data network possible.

VoIP phone Device that looks like a regular landline phone but uses VoIP to communicate over a computer network.

volatile Memory that must have constant electricity to retain data.

volts (V) Measurement of the pressure of the electrons passing through a wire, or voltage.

volume See partition.

VPN (virtual private network) Encrypted connection over the Internet between a computer or remote network and a private network.

vulnerability Weakness in a system, network, or organization that an attacker will exploit to gain access, steal information, and cause other harm.

WAN (wide area network) A widespread group of computers connected using long-distance technologies.

WAP (wireless access point) Device that centrally connects wireless network nodes.

wattage (watts or W) Measurement of the amps and volts needed for a particular device to function.

Web browser Program designed to retrieve, interpret, and display Web pages.

Web server A computer that stores and shares the files that make up Web sites.

whaling A phishing attack in which the attacker specifically targets someone high up in an organization, like the CEO.

wide area network See WAN.

Wi-Fi Common name for the IEEE 802.11 wireless Ethernet standard.

Wi-Fi 6 See 802.11ax.

Wi-Fi 6E See 802.11ax.

Wi-Fi calling Mobile device feature that enables users to make voice calls over a Wi-Fi network, rather than a cellular network.

wildcard Character—usually an asterisk (*) or question mark (?)—used during a search to represent search criteria. For instance, searching for *.docx will return a list of all files with a .docx extension, regardless of the filename. The * is the wildcard in that search. Wildcards can be used in command-line commands to act on more than one file at a time.

Windows 10 Operating system developed by Microsoft that powers most desktop and portable computers in use today.

Windows 10 Enterprise Windows edition that includes all the power and features of Windows 10 Pro for Workstations but also includes a feature called Long-Term Servicing Branch. LTSB turns off automatic updates, removes the Microsoft Store, and disables the automatic installation of Microsoft’s Edge browser. Windows 10 Enterprise is not available in stores; it has to be purchased through a Microsoft sales representative.

Windows 10 Home The most basic edition of Windows. Designed for home users, it has the fewest features. Supports up to 128 GB of RAM.

Windows 10 Pro A more robust edition of Windows, which supports up to 2 TB of RAM. Windows 10 Pro is the most basic edition that supports joining an Active Directory domain. It also allows the use of Remote Desktop Protocol and BitLocker encryption.

Windows 10 Pro for Workstations A beefier edition of Windows Pro that supports up to 6 TB of RAM and is intended for the most high-end and resource-heavy systems. Windows 10 Pro for Workstations is intended for the most high-end and resource-heavy systems.

Windows 11 Operating system developed by Microsoft and released in 2021, intended to replace Windows 10 and become the default desktop and laptop operating system.

Windows Hardware Compatibility Program Microsoft’s rigorous testing program for hardware manufacturers, which hardware devices must pass before their drivers can be digitally signed.

Windows key Key on a keyboard bearing the Windows logo that traditionally brings up the Start menu, but is also used in some keyboard shortcuts.

Windows Memory Diagnostic Windows tool that can automatically scan up to 4 GB of a computer’s RAM when a problem is encountered.

Windows PowerShell Command-line tool included with Windows. Offers a number of powerful scripting tools for automating changes both on local machines and over networks.

Windows Preinstallation Environment (WinPE) The installation program for Windows.

Windows Recovery Environment See WinRE (Windows Recovery Environment).

Windows Update Microsoft application used to keep Windows operating systems up to date with the latest patches or enhancements.

WinRE (Windows Recovery Environment) A special set of tools in the Windows setup that enables you to access troubleshooting and system recovery options.

winver Command that displays a system’s current Windows version.

wireless access point See WAP.

wireless Internet service provider (WISP) An Internet service provider for which the last segment or two uses a point-to-point long-range fixed wireless connection.

wireless mesh network (WMN) A hybrid wireless topology in which most nodes connect in a mesh network while also including some wired machines. Nodes act like routers; they forward traffic for other nodes, but without wires.

wireless repeater/extender Device that receives and rebroadcasts a Wi-Fi signal to increase coverage.

work area In a basic structured cabling network, often simply an office or cubicle that potentially contains a PC attached to the network.

workgroup A simple, decentralized network that Windows PCs are configured to use by default.

working directory The current directory used by command-line commands unless they explicitly specify a target file or directory. The prompt usually indicates the working directory.

World Wide Web (WWW) System of Internet servers that supports documents formatted in HTML and related protocols. Can be accessed by applications that use HTTP and HTTPS, such as Web browsers.

worm Similar to a virus, except it does not need to attach itself to other programs to replicate. It can replicate on its own through networks, or even hardware like Thunderbolt accessories.

WPA2 (Wi-Fi Protected Access 2) Wireless security protocol, also known as IEEE 802.11i. Uses the Advanced Encryption Standard (AES) and replaces WPA.

WPA3 (Wi-Fi Protected Access 3) The successor to WPA2, it addresses usability and security issues that affected its predecessor by including encryption to protect data of users on open (public) networks.

wrapper See container file.

WWW See World Wide Web.

x86 Describes 32-bit operating systems and software.

x86-64 Describes 64-bit operating systems and software. Sometimes known as x64.

zeroconf (zero-configuration networking) Operating system feature that provides a random Class B IP address to a system set for DHCP when a DHCP server cannot be found. Enables networking without static IP addressing in such an environment. See also APIPA.

zero-day attack Attack targeting a previously unknown bug or vulnerability that software or hardware developers have had zero days to fix.

ZIF (zero insertion force) socket Socket for CPUs that enables insertion of a chip without the need to apply pressure. Intel promoted this socket with its Overdrive upgrades, but ZIF is currently used by both Intel and AMD. The chip drops effortlessly into the socket’s pin grid array holes or land grid array, and a small lever locks it in.

zombie Computer infected with malware that has turned it into a botnet member.

zsh Command-line shell used by macOS. Short for Z Shell.