Official Facebook figures show that 600,000 unauthorised account logins take place every day. That's 1 every 140 milliseconds (the blink of an eye takes 300 to 400 milliseconds). An unauthorized account login is somebody entering your account wihout your permission. What can they do then? They can spam your friends, under your name, post links to poisoned websites with malware, use it as an important part of identity theft. What can you do to limit the risks? Change your password NOW! and do so at least once a month. Use separate and different passwords for all your accounts, not the same one everywhere, and don't make a note of them anywhere on your computer - use a little notebook, because you'll never remember them all.