ASP.NET MVC namespaces and classes are located in the System.Web.Mvc assembly. System.Web.Mvc namespace Contains classes and interfaces that support the MVC pattern for ASP.NET Web applications. This namespace includes classes that represent controllers, controller factories, action results, views, partial views, and model binders. System.Web.Mvc.Ajax namespace Contains classes that support Ajax scripts in an ASP.NET MVC application. The namespace includes support for Ajax scripts and Ajax option settings. System.Web.Mvc.Async namespace Contains classes and interfaces that support asynchronous actions in an ASP.NET MVC application System.Web.Mvc.Html namespace Contains classes that help render HTML controls in an MVC application. The namespace includes classes that support forms, input controls, links, partial views, and validation.