WP $wp )
Fires once the WordPress environment has been set up.
(WP) Current WordPress environment instance (passed by reference).
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. It is run in the main() WP method in which the $query_args are passed to parse_request(), as well as when send_headers() , query_posts(), handle_404(), and register_globals() are setup.