The Model-View-Controller (MVC) architectural pattern separates an application into three main components: the model, the view, and the controller. The MVC framework is defined in the System.Web.Mvc namespace and is a part of the System.Web namespace. The MVC pattern helps you create applications that separate the different aspects of the application (input logic, business logic, and UI logic), while providing a loose coupling between these elements. The pattern specifies where each kind of logic should be located in the application. The UI logic belongs in the view. Input logic belongs in the controller. Business logic belongs in the model. This separation helps you manage complexity when you build an application, because it enables you to focus on one aspect of the implementation at a time.