Checking in and out
When you login, you set a cookie on your machine so that you can browse the forums without having to keep re-entering in your username and password each time. Logging out clears that cookie to ensure nobody else can browse the forum as you from that PC.

To login, simply click the login link at the top left hand corner of the forum. To logout, click the logout link in the same place. In the event you cannot logout, clearing cookies on your machine will take the same effect.