Learn how to walk away from your Mac without worrying about others easily getting access to your data or messing up your settings. By setting your Mac to log you out, or require a password when you have left it, you can walk away from a Mac in a semi-public area like your work space or home office.
Gary, I would like to add, to lock your Mac quickly, you can hit Control+Shift+Eject, and put it to sleep, Command+Option+Eject.
Again, as always great video. ^^