Zend_Controller is the heart of Zend Framework's
MVC system. MVC stands for Model-View-Controller
and is a design pattern targeted at separating application logic
from display logic. Zend_Controller_Front implements a
Front
Controller pattern, in which all requests are
intercepted by the front controller and dispatched to individual
Action Controllers based on the URL requested.
The Zend_Controller system was built with extensibility
in mind, either by subclassing the existing classes, writing new
classes that implement the various interfaces and abstract classes
that form the foundation of the controller family of classes, or
writing plugins or action helpers to augment or manipulate the
functionality of the system.