Over time, you might log onto Facebook using many different devices – and forget to sign out. This can grow to a pretty long list of office computers, your friends' tablets, smartphones or other devices.
In the "Security and Login" section of Facebook's settings, you'll find a list of the device, location, date and time of each Facebook login.
You can also remove individual devices or end active sessions with a mouse click – for example, if your account is accessed from a suspicious location. At the bottom right of the list, you'll find a button that ends all active sessions. — dpa