From PHPBuilder.com today, there's a new tutorial that looks at one of the more handy features built into PHP, one that makes personalized sites a whole lot easier - sessions - and their management.

In a nutshell, sessions are the way that we "maintain state" from one page to the next, that is, how we identify specific users across multiple page requests.

When the user comes to the site, we need to be able to give them a unique identifier (a session id) that will allow us to know the difference between each user on the site. So, when the user logs in, and then modifies their choices for foo.php, we know whose profile to save those changes to.

The article goes on to talk about what sessions really are, how they're handled on both the client and server side, and a simple code example of how to check the value of them. Thankfully, they also include a section on session vulnerabilities, showing how with something as simple as some Javascript, a session can be maipulated.

To help prevent this, they give some examples of securing your sessions. Then, to illustrate all of the above points, they provide some simple code validate the session information that's been set.