[SEOvB]

A plugin is like a php file edit, or including a php file into vBulletin to add some sort of functionality or to display information.

A phrase is just like a language file in the sense that if you use something like $vbphrase[register] people from different languages can edit that phrase rather then ahving to manually edit the templates

You creat plugins, from the AdminCP -> Plugin Manager -> Add New Plugin

The hook locations are different locations where the plugin gets executed, for example the global_start hook will execute a plugin at the start of every page, and something like a forumdisplay_complete plugin will execute on forumdisplay pages.

I think