Facebook team work very hard to develop the Facebook everyday. Especially they are very particular about users’ privacy and security. Few days ago they introduced Social Authentication instead of using usual CAPCHA’s. Now they have developed another great feature to protect your facebook account.
This shows you from where you have logged in to Facebook recently. This is actually a tracking system. You can always get a notification to your email or to your mobile (as a text message) whenever a computer or a mobile device is logged in to your Facebook account. If you track down any suspicious activity you can immediately disconnect the suspicious activity by clicking on End activity and then you can go for a password change.