To understand rooting, it is essential to understand how Unix-like systems work. The original Unix operating system, on which Linux and other Unix-like systems are based, was designed from the very beginning as a multiuser system. This is primarily because personal computers did not yet exist and hence it was necessary to have a mechanism for separating and protecting the resources of the individual users while allowing them to use the system simultaneously. But in order to perform privileged tasks such as granting and revoking powers for ordinary users and accessing critical system files to repair or upgrade the system, it was necessary to have a system administrator account that has superuser access. So, we have two types of accounts: normal user accounts that have fewer privileges and a superuser or root account that has all of the privileges.

Hence, root is the username or account that by default has access to all commands and files on a Linux or other Unix-like operating system. It is also referred to as the root account, root user, and the superuser. So, in Linux, the root user has the power to start/stop any system service, edit/delete any file, change the privileges of other users, and so on. We have learned earlier that Android uses the Linux kernel and hence most of the concepts present in Linux are applicable to Android as well. However, when you buy an Android phone, normally it does not let you log in as a root user. Rooting an Android phone is all about gaining this root access on the device to perform actions that are not normally allowed on the device.

It is also important to understand the difference between rooting and jailbreaking, as both are often wrongly assumed to be the same. Jailbreaking a device running an Apple iOS operating system allows you to remove certain restrictions and limitations put in place by Apple. For instance, Apple does not allow sideloading unsigned applications on the device. So, by jailbreaking, you can install applications that are not approved by Apple. In contrast, Android by functionality allows sideloading of applications. Jailbreaking a phone involves bypassing several security restrictions simultaneously. Hence, gaining root access on the device is only one of the aspects of jailbreaking a device.