WordPress at a glance
action is not described

wp_enqueue_scripts action-hook . WP 2.8.0

Fires when scripts and styles are enqueued.

Usage

add_action( 'wp_enqueue_scripts', 'action_function_name_2509' );
function action_function_name_2509(){
	// action...
}

Where the hook is called

wp_enqueue_scripts()
wp-includes/script-loader.php 2231
do_action( 'wp_enqueue_scripts' );

Where the hook is used (in WP core)

wp-includes/customize/class-wp-customize-selective-refresh.php 163
add_action( 'wp_enqueue_scripts', array( $this, 'enqueue_preview_scripts' ) );
wp-includes/class-wp-customize-widgets.php 1058
add_action( 'wp_enqueue_scripts', array( $this, 'customize_preview_enqueue' ) );
wp-includes/widgets/class-wp-widget-media.php 110
add_action( 'wp_enqueue_scripts', array( $this, 'enqueue_preview_scripts' ) );
wp-includes/widgets/class-wp-widget-text.php 61
add_action( 'wp_enqueue_scripts', array( $this, 'enqueue_preview_scripts' ) );
wp-includes/default-filters.php 481
add_action( 'wp_enqueue_scripts', 'wp_localize_jquery_ui_datepicker', 1000 );
wp-includes/default-filters.php 483
add_action( 'wp_enqueue_scripts', 'wp_common_block_scripts_and_styles' );
wp-includes/class-wp-customize-nav-menus.php 1177
add_action( 'wp_enqueue_scripts', array( $this, 'customize_preview_enqueue_deps' ) );