WordPress at a glance
action is not described

widgets_init action-hook . WP 2.2.0

Fires after all default WordPress widgets have been registered.

Usage

add_action( 'widgets_init', 'action_function_name_6896' );
function action_function_name_6896(){
	// action...
}

Where the hook is called

wp_widgets_init()
wp-includes/widgets.php 1661
do_action( 'widgets_init' );

Where the hook is used (in WP core)

wp-includes/class-wp-customize-widgets.php 104
add_action( 'widgets_init', array( $this, 'register_settings' ), 95 );
wp-includes/class-wp-widget-factory.php 32
add_action( 'widgets_init', array( $this, '_register_widgets' ), 100 );