WordPress at a glance
action is not described

wp action-hook . WP 2.1.0

Fires once the WordPress environment has been set up.

Usage

add_action( 'wp', 'action_function_name_2458' );
function action_function_name_2458( $this ){
	// action...
}
$this(WP)
Current WordPress environment instance (passed by reference).

Changelog

Since 2.1.0 Introduced.

Where the hook is called

WP::main()
wp
wp-includes/class-wp.php 758
do_action_ref_array( 'wp', array( &$this ) );

Where in WP core the hook is used WordPress

wp-includes/class-wp.php 355
add_action( 'wp', array( $this, 'customize_register' ) );