If you have a website which a user can join then you need a way to keep track of that person as they navigate through the site. Not for reasons of spying on them or anything like that, but purely in order to keep them logged in and to offer them all the benefits that membership offers.

The Figure shows this plug-in being used to create a session and read back one of the session variables.

Creating a PHP session allows you to maintain a user's details across multiple pages