System.Web.Mvc assembly contains all classes and interfaces to support ASP.NET MVC Framework
MVC design pattern splits application into three main parts : Model, View and Controller
Model– Model represents a set of classes which describe the business logic i.e. business model as well as data model. It also defines business rules for data means how the data can be changed and manipulated.
View– View represents the UI components. It displays the data that is received from the controller as the result. It is responsible for transforming the model into UI.
Controller – Controller is responsible for processing incoming requests. It receives input from users via the View, then process the user’s data with the help of Model and passing the results back to the View. Typically, it acts as the coordinator between the View and the Model