While it's very easy and straightforward to use and may suffice for your needs, it lacks some of the advanced features that the PHPLib provides. Basic Terms Session management is a mechanism to maintain state about a series of requests from the same user across some period of time. The problem is, that HTTP has no mechanism to maintain state. Individual requests aren't related to each other. The Web server can't easily distinguish between single users and doesn't know about user sessions.
Session management refers to the way that associate data with a user during a visit to a Web page.
This tutorial uses the term session for a single visit of a user. For example, a typical online shopping session might include logging in, putting an item into the shopping cart, going to the checkout page, entering address and credit card data, submitting the order, and closing the browser window. PHP 4.0 includes native session management functions to ease the task of managing user sessions. Without the serializing feature, it wouldn't be possible, for example, to store PHP arrays into a database. Serializing data is very useful for preserving data across requests, an important facet of a session library.