Описание тега actionmethod
Action methods typically have a one-to-one mapping with user interactions. Examples of user interactions include entering a URL into the browser, clicking a link, and submitting a form. Each of these user interactions causes a request to be sent to the server. In each case, the URL of the request includes information that the MVC framework uses to invoke an action method.
Most action methods return an instance of a class that derives from ActionResult. The ActionResult class is the base for all action results. However, there are different action result types, depending on the task that the action method is performing. For example, the most common action is to call the View method. The View method returns an instance of the ViewResult class, which is derived from ActionResult.
You can create action methods that return an object of any type, such as a string, an integer, or a Boolean value. These return types are wrapped in an appropriate ActionResult type before they are rendered to the response stream.