In this new tutorial on the PHPRefresher.com site, Anand Godar walks you through just about all of the session functionality that comes with PHP and includes some code snippets for explanation.

Due to the fast evolution of Web programming, the stateless nature of the HTTP protocol brought many problems to certain Web applications that required maintaining their state across several HTTP requests. This demanded a rapid development of several mechanisms aimed at tackling this issue through diverse methods. Then a session management emerged as a direct response to the above mentioned problem, and currently this mechanism is being used by PHP developers worldwide, in cases where a Web application needs to keep track of its “state” during the occurrence of different HTTP requests.

The article starts off with the basics of sessions - what they are, how they're handled and created by PHP - and moves into the specific functions and their use. He talks about starting/ending sessions, their IDs, caching, module handling and working directly with the session cookie (if it exists).