ASP.NET MVC 4 is a framework for developing highly testable and maintainable Web applications that follow the Model-View-Controller (MVC) pattern. The framework encourages you to maintain a clear separation of concerns— views for UI, controllers for handling user input, and models for domain logic. ASP.NET MVC applications are particularly suited for unit testing and using test-driven development (TDD) techniques. ASP.NET MVC 4 makes it easy to write applications for the mobile web through adaptive rendering and device specific display modes.

ASP.NET MVC 4 also includes ASP.NET Web API, a framework for building and consuming HTTP services that can reach a broad range of clients including browsers, phones, and tablets. ASP.NET Web API is great for building services that follow the REST architectural style, plus it supports RPC patterns.