Magento PHP Developer's Guide

The controller

At its core, Magento is a Model-View-Controller (MVC) framework, so in order to make our new route functional, we have to create a new controller that will respond to this specific route. To do this, perform the following steps:

1. Navigate to the extension root directory.
2. Create a new folder called controllers.
3. Inside the controllers folder create a file called IndexController.php.
4. Copy the following code:

   The file location is app/code/local/Mdg/Hello/controllers/IndexController.php.

   <?php 
   class Mdg_Hello_IndexController extends Mage_Core_Controller_Front_Action
   {
        public function indexAction()
     {
        echo 'Hello World this is the default action';
        }
   }