Linux is a multi-user system, allowing many users on the same machine at once. Due to security considerations, normal users are limited to manipulating only their personal files. Sometimes, however, it is needed to administer the system, to install software or perform maintenance tasks. To perform these tasks, a linux system has a special user account called root.
Using the root account could be very dangerous. One short command might wipe out your entire hard drive without warning. Therefore, you must observe extreme caution while working as root, avoiding root as much as possible.
Finally, remember what sets off the hitch-hickers guide to the galaxy from the encyclopedia Galactica: It has, written on its top, the phrase: Don't Panic!
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