Root

"Unix-style computer operating systems, root is the conventional name of the user who has all rights or permissions in all modes (single- or multi-user). Alternative names include baron in BeOS and avatar on some Unix variants. BSD often provides a toor ("root" backwards) account in addition to a root account. The root user can do many things an ordinary user cannot, such as changing the ownership of files and binding to ports numbered below 1024.

It is never good practice for anyone to use root as their normal user account because simple typographical errors in entering commands can cause major damage to the system. It is recommended to create a normal user account instead and then use the su command to switch when necessary. Some use the sudo utility instead, which allows a measure of graduated access.

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For a full description please visit http://en.wikipedia.org/wiki/Superuser