This action hook runs immediately after the global WP class object is set up. The $wp object is passed to the hooked function as a reference (no return is necessary).
This hook is one effective place to perform any high-level filtering or validation, following queries, but before WordPress does any routing, processing, or handling.
The 'wp' hook is found in
/wp-includes/class-wp.php, within the main() method of the WP() class.