What is the relation Block, Model, Controllers MVC in magento?

             A quick primer on MVC: When a page in Magento is called, the URL tells Magento what code to run. This is done via a “router” which calls upon a selected Controller to do it’s thing. The URL gets “routed” to a particular Controller, which in turns tells Magento what to do. The Catalog controller, for instance, is responsible for telling Magento to load a product collection and and then show those products to us. The Controller tells Magento which layout is to be used. This determines which modules are put into place, which in turn tells Magento what Views to output. The data from the Models are given to the Views to be displayed. In the scheme of things here, Blocks fit roughly between the View and the Model.