Model–View–Controller (MVC) is a software architecture. Magento is a skyscraper when we talk about architecture. Following articles describe various of topics related to Magento MVC.
Layout of your custom controller in Magento?
When you work with custom (your own) controllers in Magento,
either frontend or backend, you will probably also use existing blocks and models or if needed write your own classes.
But what happens if you want to or have exigency to move/remove common blocks?
Can you really “design” your own page view without touching Cascading Style Sheets?