Understanding WordPress Hooks: Actions and Filters Explained (2026)

WordPress hooks are the backbone of WordPress development. Nearly every plugin and theme you use relies on them — and if you want to build or customize anything in WordPress, you need to understand how hooks work.

If you found this page, you’ve probably been trying to modify some behavior in WordPress and hit a wall. Maybe someone told you to “just add a filter” or “hook into this action” and you weren’t sure what that meant. I’m going to change that in the next few minutes.

What Are WordPress Hooks?

Hooks are execution points inside WordPress Core where you can inject your own code. WordPress runs through its process — loading plugins, building pages, querying the database — and at key moments it “opens a door” and says: “Hey, anyone want to run some code here?”

That’s a hook. Two types:

Actions — do something when a specific point fires
Filters — modify data before it’s used or saved

The difference matters, and it’s simpler than it sounds.

Actions vs. Filters — The Short Version

An action is a signal that says “this thing happened.” You respond to it. You don’t expect anything back.

A filter is a middleman that takes some data, lets you change it, and passes it along. You always have to return something.

Think of it this way:

Action = dispatching a message: do_action('event_name')
Filter = editing a document: apply_filters('field_name', $value)

Actions fire and forget. Filters receive, modify, and return.

How to Hook In: add_action and add_filter

Both functions share the same signature. The only difference is which one you call:

add_action( 'hook_name', 'your_function', priority, accepted_args );
add_filter( 'hook_name', 'your_function', priority, accepted_args );

Let’s break this down with real examples.

Adding an Action

Run your own code when WordPress publishes a post:

function my_custom_publish_notice( $post_ID ) {
    // Send a notification, log to external service, etc.
    error_log( "New post published: $post_ID" );
}
add_action( 'publish_post', 'my_custom_publish_notice' );

Adding a Filter

Modify the post title before it hits the database or gets displayed:

function add_prefix_to_title( $title ) {
    return '[NEW] ' . $title;
}
add_filter( 'the_title', 'add_prefix_to_title' );

The filter receives the current value, you modify it, and you return the new value. Always return something — if you don’t, the filtered value becomes empty or broken.

The Priority Parameter

Multiple functions can hook into the same hook. The priority parameter controls execution order — lower numbers run first. Default is 10.

// Runs first (priority 5)
add_filter( 'the_content', 'function_a', 5 );

// Runs second (priority 10, the default)
add_filter( 'the_content', 'function_b', 10 );

// Runs third (priority 20)
add_filter( 'the_content', 'function_c', 20 );

If two functions touch the same data and you need a specific order, adjust the priority. If you want yours to run after most other things, use a high number like 99 or 999.

Removing a Hook

You can also disconnect a function from a hook:

remove_action( 'hook_name', 'your_function', priority );
remove_filter( 'hook_name', 'your_function', priority );

Note that you need the exact same priority you used when adding it. If you added it with priority 10, you must remove it with priority 10.

Removing a Hook from a Class-Based Plugin

Regular functions are globally accessible, but class methods live inside the class. To remove them:

// When added like this in the plugin:
add_action( 'hook_name', array( $this, 'method_name' ), 10 );

// You remove it like this:
remove_action( 'hook_name', array( $this, 'method_name' ), 10 );

// Or globally, if you have an instance:
global $plugin_class_instance;
remove_action( 'hook_name', array( $plugin_class_instance, 'method_name' ), 10 );

I covered this in detail with a worked example in this post on removing hooks from class-based plugins.

Common Hooks You’ll Use

These are the ones I reach for most often during WordPress development:

Hook	Type	When It Fires
`init`	Action	After WordPress finishes loading
`wp_head`	Action	In the <head> section of front-end pages
`wp_footer`	Action	Before the closing </body> tag
`the_content`	Filter	Post/page content is retrieved
`the_title`	Filter	Post title is retrieved
`wp_enqueue_scripts`	Action	When scripts and styles should be loaded
`after_switch_theme`	Action	When a new theme is activated
`admin_init`	Action	When admin pages initialize
`save_post`	Action	When a post is saved in the database
`pre_get_posts`	Action	Before WP_Query runs (modify the query)

Finding the Right Hook

WordPress has hundreds of hooks. The trick is finding the right one for what you’re trying to do.

The best approach: search the codebase. If you know what function or file runs the behavior you want to modify, look at what hooks it calls nearby. Install a local WordPress install, crack open VS Code, and search for do_action or apply_filters near the relevant code.

There are also reference resources — the official WordPress Reference documents every hook with its parameters and an example. That should be your starting point whenever you’re not sure which hook to use.

Beyond the Basics

Once you’re comfortable with the fundamentals, there are a few things that separate beginner hook usage from clean, professional hook usage:

Use a unique prefix on your function names to avoid collisions with other plugins. my_plugin_do_something() instead of do_something().
Remove hooks cleanly — only remove what you own. Never remove another plugin’s hooks without checking first if there’s an official API for that.
Document your hooks. If you’re building something for a client, note which hooks you’re using and why, so future developers aren’t hunting blind.
Use closures sparingly. Anonymous functions (closures) can’t be removed by other plugins. Named functions are better for anything that might need to be unhooked.

If you’re building custom functionality in WordPress, hooks are what make it modular. You can add them, remove them, and they’re the reason WordPress plugins can coexist without stepping on each other constantly.

Wrapping Up

Hooks are WordPress’s plugin architecture. Action hooks let you respond to events. Filter hooks let you reshape data. Master these two concepts and you’ll never wonder “how do I modify this?” again — you’ll just look for the right hook and write your code.

If you found this page useful, drop a comment — I read them. And if you’re building something in WordPress and running into a specific challenge, I’m happy to help you figure out which hook you need.