WordPress at a glance
action is not described

wp_loaded action-hook . WP 3.0.0

This hook is fired once WP, all plugins, and the theme are fully loaded and instantiated.

Ajax requests should use wp-admin/admin-ajax.php. admin-ajax.php can handle requests for users not logged in.

Usage

add_action( 'wp_loaded', 'action_function_name_5112' );
function action_function_name_5112(){
	// action...
}

Where the hook is called

In file: /wp-settings.php
wp_loaded
wp-settings.php 488
do_action( 'wp_loaded' );

Where the hook is used (in WP core)

wp-includes/class-wp-customize-widgets.php 112
add_action( 'wp_loaded', array( $this, 'override_sidebars_widgets_for_theme_switch' ) );
wp-includes/class-wp-rewrite.php 1429
add_action( 'wp_loaded', array( $this, 'flush_rules' ) );
wp-includes/class-wp-rewrite.php 1749
add_action( 'wp_loaded', array( $this, 'flush_rules' ) );
wp-includes/default-filters.php 442
add_action( 'wp_loaded', '_custom_header_background_just_in_time' );
wp-includes/class-wp-customize-manager.php 368
add_action( 'wp_loaded', array( $this, 'wp_loaded' ) );