WordPress at a glance
action is not described

user_register action-hook . WP 1.5.0

Fires immediately after a new user is registered.

Usage

add_action( 'user_register', 'action_function_name_9405' );
function action_function_name_9405( $user_id ){
	// action...
}
$user_id(int)
User ID.

Changelog

Since 1.5.0 Introduced.

Where the hook is called

wp_insert_user()
user_register
wp-includes/user.php 1854
do_action( 'user_register', $user_id );

Where the hook is used (in WP core)

wp-admin/includes/admin-filters.php 97
add_action( 'user_register', array( 'WP_Internal_Pointers', 'dismiss_pointers_for_new_users' ) );
wp-includes/ms-default-filters.php 87
add_action( $action, 'wp_maybe_update_network_user_counts', 10, 0 );