The system administrator is responsible for maintaining the system. On a single-user system, you are the system administrator. On a small, multiuser system, you or another user acts as the system administrator, or this job may be shared. On a large, multiuser system or network of systems, there is frequently a full-time system administrator. When extra privileges are required to perform certain system tasks, the system administrator logs in as the root user by entering the username root and the root password or uses the sudo utility to run commands directly. While logged in in this manner, this user is called Superuser or administrator. On a multiuser system, several trusted users may be given the root password. Do not work as Superuser as a matter of course. When you have to do something that requires Superuser privileges, work as Superuser for only as long as you need to; revert to working as yourself as soon as possible.
A terminal emulator, such as the Terminal utility, allows you to use the Mac OS X command line interface from a graphical environment. You can use a terminal emulator to launch both textual and graphical programs.
The man utility provides online documentation on system utilities. This utility is helpful to new users as well as to experienced users who must often delve into the system documentation for information on the fine points of a utility's behavior. The info utility helps the beginner and expert alike. This utility includes a tutorial on its use and documentation on many utilities.
As with many operating systems, your access to a Mac OS X system is authorized when you log in. You can change your password at any time. Choose a password that is difficult to guess and that conforms to the criteria imposed by the utility that changes your password.