On a new post to the php|architect site today Giorgio Sironi takes a look at namespaces in PHP from a beginner's perspective.

According to the official documentation, PHP namespaces have been designed to prevent name collisions between classes from different packages and to avoid the use of very long names in the code to refer to classes or functions. [...] This means that namespaces help a developer write code that is both more concise and clearer - a direction which is always an improvement towards expressiveness.

He gives an example of how to define them in your application (using the "namespace" operator), how they work on a bit more detailed level and a few exceptions you'll need to watch out for. He also talks about importing other classes into namespaces and how you can use the dynamic loading of classes right beside the namespace functionality.