Logging out/off - Switching Users


When you select log off you will be faced with a number of choices,
Network versions
Often your required to choose  "Close all programs and log on as different user?" and then only switch off the monitor, this allows updates to be done whilst it's logged off. 
In these days of saving energy this is getting rarer. If you are told to leave your PC on at least turn of your monitor.
"Stand By" not to be used on laptops if your not on mains power and only really used by homeusers. 
"Turn Off" does what it says on the tin, wait for it to finish then kill the power (screen, PC, sound, everything).
"Restart" often you might do this if you've added a new program. Or testing new start up routines 
If you just want to walk away from your PC for a while do Ctrl,Alt,Del - "Shutdown" - "Standby" and make sure your password protected.