Action
Quick Definition
An action is a type of WordPress hook that lets you run custom code at a specific point during execution. Unlike filters, actions do something but don't return data — like sending an email when a post is published.
What Is an Action?
An action is one of the two types of WordPress hooks (the other being filters). According to the Plugin Handbook, "actions provide a way for running a function at a specific point in the execution of WordPress Core, plugins, and themes."
The key distinction from filters: action callbacks do not return anything. They execute code — send an email, write to the database, output HTML, log an event — and then exit. They act on something rather than modifying something.
Think of it this way:
- Actions = "When X happens, also do Y"
- Filters = "Before X is used, change it to Z"
Actions in Practice
You register actions with add_action():
add_action('hook_name', 'your_function', priority, args);Parameters:
- hook_name (required) — which action to hook into
- callback (required) — your function to run
- priority (optional, default: 10) — execution order (lower = earlier)
- accepted_args (optional, default: 1) — how many parameters your function receives
Example — sending a notification when a post is published:
add_action('publish_post', 'notify_admin');
function notify_admin($post_id) {
wp_mail('admin@example.com', 'New Post', 'A new post was published.');
}Common WordPress actions:
init— fires after WordPress loads, before any outputwp_head— fires inside<head>wp_footer— fires before</body>wp_enqueue_scripts— the proper way to load CSS and JavaScriptsave_post— fires when a post is savedadmin_init— fires on every admin page load
Use do_action() to create your own actions, and remove_action() to detach a callback.
Why It Matters
Actions are the backbone of WordPress's event-driven architecture. Every plugin that adds a feature does it through actions. See our plugins guide and code snippet plugins.