1 What is the Administrative User

Linux (and other Unix systems) have an administrative user called root. Windows has an administrative user called Administrator (and may have other users with administrative privileges).

The administrative user has the "power" to make any and all changes to the system.

2 Linux Variants

Some Linux systems allow the root user to login (Redhat, for example) while others do not (Ubuntu, Debian). Some commands (like the init command) require that you have root privilege.

You can gain root privilege for a command by using the sudo command. For example, on Ubuntu, you can type: sudo init. (Note: For Redhat, you will need to specify the full pathname /sbin/init.)