Answer:   Dependency Resolver again has been introduced in MV?C3 and it is greatly simplified the use of dependency injection in your applications. This turn to be easier and useful for decoupling the application components and making them easier to test and more configurable.

Answer:   A dependency resolver is just a service locator integrated with the ASP.NET MVC codebase. Resolvers are a way to add the implementation of the Dependency Inversion principle into an existing (large) codebase.