How to find which modules are implementing a hook in Drupal 7

Many of you know, hooks are the way to extend drupal. Each and every module implement a hook to extend drupal functionality. For, debugging purpose or for any other reason if you want to know which are modules implementing a certain hook you can use below function.

<?php

$modules = module_implements($hook, $sort = FALSE, $reset = FALSE);

?>

$hook should be replaced by hook name like 'menu' or 'help'

$sort if repalced by TRUE modules are sorted by title name

$modules contains array of module names that are implementing $hook that we provided in the function.