3.5 Understanding Model Entities and Resource Models
One of the biggest differences between Magento and every other CMS platform is in the way data is stored and accessed. In general, models are used to talk to the database, represent the data in object-oriented fashion and perform a business logic. But, if we want to further abstract things, we should mention that Magento uses a three-layer approach for models. We have entity models, resource models and collections.