Before we start toying with any injectable device, let's refresh on some what the development and functions of a universal serial board. Around the mid-1990s, several of the leading tech companies joined forces to create a more reliable, efficient means of connecting personal computers with external electronics with more feasibility and streamlining better transfer rate, with less configuration to be dealt with from previous standards (like the PS/2 connectors). This led to several changes for other peripherals and network development. We could classify them into four different categories. Input peripherals would be your keyboard and mice or even a scanner and output devices such as speakers and printers.

One USB device worth mentioning is the USB hub with its main purpose for providing an extension for a single port expansion into multiple ports allowing multiple functions to be connected at the same time as it operates logically with a bus system. Devices that fall under communication could include a microphone or webcam. The last is for storage purpose, which includes the flash drive, external hard drive, and CD drives. The one we'll particularly focus on is the USB MSC/UMS providing efficiency as a external hard drive for transferring files between computers. The modern flash drive that you would normally see most folks using for data storage, file backup or data transfer is usually contained in a durable case that may come in various designs, but they'll all serve the same purpose. These quickly replaced the floppy disc, which had a lot of downside from requiring an optical reader, lower storage, reliability and that it can be harm electromagnetic interference. The USB connection may also acts as the power supply to peripheral devices. Most should have a type-A male connection, which is standard for USB drives and all dominating operating system. It's not uncommon to see that portable digital storage is more integrated than you may think.

Following is an image of a USB flash drive:

A USB has a micro-controller, in a flash you may see a small part that's the closer to the connecter which is the firmware controller and the most easily seen component is the mass storage. There are multiple steps that occur when your USB can initialize with a port. For a USB device, the moment it first fully connects with universal plug and play, the device is provided power which then starts up the firmware. The response with a request to set address, in return the device descriptor is provided and the driver is then loaded with the configurations syncing. It is possible to get a device with multiple descriptors (such as mic and cam) if there are multiple functions that flows through that single USB. In simple words, the descriptor is what tells that host what the device is.