Difference between Action Hook and Filter Hook in WordPress

Hooks are the real power and the magic of WordPress.

The Action Hooks add new functionality (using add_action()), while Filter Hooks manipulate the post content (using add_filter()).

add_action( 'init', array( $this, 'my_callback' ) );
add_filter( 'the_content', array( $this, 'my_callback' ) );

The Filter hooks always return a value, unlike Action hooks which do not return a value.

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