Wes Shell has posted a new tutorial to his blog today looking at encapsulation in PHP development - containing parts of the script to make them easier to work with as a whole.

In order to understand the purpose of encapsulation you first need to understand the purpose of classes. [...] In order for them to be used properly as they were designed, you will need to limit how users of the class can interact with those characteristics and functionality.

He looks at the visibility modifiers (public/private/protected), interface functions and some sample code showing how to use them in a simple class to work with a Person's set of data.