There's one thing that coders look for when they get past the most basic bits of PHP - a way to store information between the requests. Thankfully, PHP has that functionality build in (for quite a while now, actually) and it's very easy to use. Sessions make storing data simple and, according to this new post on the Zend Developer Zend, there's even more fun things you can get them to do - with the right convincing.
By default, session data is stored on the filesystem in individual files. This works fine for most people, but when it comes to storing session data, PHP has several options available. This article will discuss some of the built-in options for session storage and also show you how to write your own session handler.
They cover some of the options that you can alter (in the php.ini) to change the defaults for your sessions, including where they're written to. With those basics out of the way, the real meat of the tutorial comes in - the creation of a custom session handler. They base theirs on a few simple functions like open, read, write, destroy, etc. There's no code for those functions, but they do provide good descriptions for what they should do. To wrap it all up, they give the "howto" on actually using this functionality in your application.