add_action( string $tag, callable $function_to_add, int $priority = 10, int $accepted_args = 1 )

Hooks a function on to a specific action.


Actions are the hooks that the WordPress core launches at specific points during execution, or when specific events occur. Plugins can specify that one or more of its PHP functions are executed at these points, using the Action API.



(string) (Required) The name of the action to which the $function_to_add is hooked.


(callable) (Required) The name of the function you wish to be called.


(int) (Optional) Used to specify the order in which the functions associated with a particular action are executed. Lower numbers correspond with earlier execution, and functions with the same priority are executed in the order in which they were added to the action.

Default value: 10


(int) (Optional) The number of arguments the function accepts.

Default value: 1


(true) Will always return true.

More Information


add_action( $hook, $function_to_add, $priority, $accepted_args );

To find out the number and name of arguments for an action, simply search the code base for the matching do_action() call. For example, if you are hooking into ‘save_post’, you would find it in post.php:

do_action( 'save_post', $post_ID, $post, $update );

Your add_action call would look like:

add_action( 'save_post', 'wpdocs_my_save_post', 10, 3 );

And your function would be:

function wpdocs_my_save_post( $post_ID, $post, $update ) {
   // do stuff here


File: wp-includes/plugin.php

function add_action( $tag, $function_to_add, $priority = 10, $accepted_args = 1 ) {
	return add_filter( $tag, $function_to_add, $priority, $accepted_args );


Version Description
1.2.0 Introduced.

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