It’s disturbing just how many people seem to leave their computers permanently logged in to online services.
Yes, an admin password can prevent a passer-by from installing a keylogger on your computer without your knowledge, but just *what* have you left your computer logged into from its desktop browser?
Sometimes an XKCD cartoon can tell it better than words.
The moral? Remember to log out.
And if you want to do an even better job of keeping your information secure, use some kind of full disk encryption.
If your computer’s hard disk isn’t fully encrypted, a determined thief might be able to access your data after stealing the device, whether or not the computer is logged in or not.