Hooks List

hooks helps you handle part of source code without editing core files. There is two type of hooks : Events hooks and Filter Hooks.
Events hooks let you execute a specific part of code within a function (or method) at a particular moment.
Filter Hooks let you edit part of variables passed through a specific function (or a method also) at a particular moment.

Here is the list of Events Hooks and Filter Hooks

List of Events Hooks

user_creation_fields : it let you edit/add custom field to user creating form