The Magento version of MVC
If you are familiar with traditional MVC implementations such as CakePHP or Symfony, you may know that the most common implementation is called a convention-based MVC. With a convention-based MVC to add a new Model, or let's say a Controller, you only need to create the file/class (following the framework conventions); the system will pick it up automatically.
Magento on the other hand uses a configuration-based MVC pattern, which means creating our file/class is not enough; we have to tell Magento explicitly that we have added a new class using configuration files written in XML.
Each Magento module has a
config.xml file that is located under the module's
etc/ directory and contains all the relevant module configurations. ...