[Developer]

What is a hook:

Hooks are basically locations in the vBulletin files, where code can be executed using the plugin system.

So for instance, if a location in the User CP has a hook, you can execute code there - using the plugin system. Of course, actual file modifications can still be executed anywhere you want.

If a location does not have a hook, you will either HAVE to modify the files (something that 3.5 modders try to avoid now, like me) OR you just don't insert the code in the file, and instead ask Jelsoft to add a hook there.

Makes sense?