whenever i connect to anandtech forum via the url forums.anandtech.com, i always see a link on the top right hand side of the screen saying "there are xxxx members logged".. and when u click on it, u will see a list of users that are currently logged in in the forum.. i was wondering how does the forum check and see if a user is logged in or not and how does it update the number of users if someone logged out or left the forum?