What are the types of hooks in WordPress and mention their functions?

In WordPress, there are primarily two types of hooks: Action Hooks and Filter Hooks. Both are used to extend or modify WordPress functionality, but they serve distinct purposes and functions.

Action Hooks

Action Hooks enable you to insert custom code at specific points during the WordPress execution process. This allows you to trigger your custom functions in response to certain events. For instance, wp_head is a frequently used Action Hook that fires when WordPress generates the page header. If you wish to add a custom CSS file or JavaScript file to your site's header, you can utilize this hook. Example:

php
function add_custom_css() {
    echo '<link rel="stylesheet" type="text/css" href="custom-style.css">';
}
add_action('wp_head', 'add_custom_css');

This code adds a custom CSS file to the page header using the wp_head hook.

Filter Hooks

Filter Hooks are used to modify WordPress data, allowing you to process or replace data before it is sent out. These hooks typically act on post content, titles, or comments. For example, the_content is a Filter Hook that allows you to modify post content. Example:

php
function modify_content($content) {
    return $content . '<p>This is a paragraph automatically added at the end of the post.</p>';
}
add_filter('the_content', 'modify_content');

This code appends a paragraph to the post content using the the_content hook.

Summary

Action Hooks are mainly used to trigger custom functions at specific points in the WordPress execution flow, whereas Filter Hooks are used to modify or filter WordPress data. By appropriately utilizing both types of hooks, you can highly customize and extend WordPress functionality to better meet personal or business needs.