What is controller in MVC

The controller generally accepts requests and fires an action. i.e. You may request index.php/admin/users/view/id/123

Your controller in the above example is Users firing the view Action it got from the request (usually another object).

Sorry for the double comment ... you can see the controller in action at http://code.google.com/p/sharpy/ ... which is my less than a week old PHP framework.