The root user is the administrative user with complete control over the system and administrative privileges. A root user is created during the installation of Linux and has the user ID 0. They can access all files, directories, and resources on the system and perform any action, including system-wide changes and modifications.

It is essential to have the root user because they can manage the system, install software, configure network settings, and perform other system-level tasks. It is essential, however, to use the root account with caution, as any mistake or malicious action taken by the root user can have severe consequences and affect the entire system.

To prevent accidental damage to the system, it is recommended to use the root account sparingly and create separate user accounts with limited privileges for everyday tasks instead. A good security practice is to use sudo to perform administrative tasks as a regular user, which requires authentication and restricts the scope of what can be executed by the command.