Plugin Hooks for a PHP application

[ZiNgA BuRgA]

The idea of hooks is basically to execute a custom function at a certain point in time.

There are in fact many possible different ways this can be implemented.
If you want a MyBB like approach, where a plugin adds hooks, and the main script executes them, all you need to do is provide something to store the hooks (hint, an array), and something which will loop through the list and execute them.