When you finish using your computer and leave the area, you should probably log out so that no one can wander in and gain access to your files, email account, etc. If you have a user name on a network, everything done on the computer with this identifier is considered your work. Imagine if someone were to enter incorrect data or to conduct improper behavior on your account, and it was traced back to you. Logging out helps keep the system secure.
An alternative to logging out is to lock the screen, as described in the next section, and unlock it when you come back. But logging out gives other people a chance to use your system.
Whereas logging out leaves your computer running, shutting down terminates all processing so that the hardware can be powered off. Many people let their Linux workstations run day and night, without shutting them down. In some organizations, your idle workstation joins in as part of a supercomputing grid during the evening hours. Since Linux computers can run months and even years without having to restart, you may not have to shut down your JDS system.
However, if you want to turn off your computer, you must first shut down JDS to ensure that you don’t lose any data or corrupt any files. Some computers automatically turn off the power at the end of the shutdown sequence. (Usually, the monitor is still running, though, and needs to be turned off by hand.) Other computers require that you manually turn off the power switch ...