ASP.NET MVC #2 - Introduction to ASP.NET MVC 4

In terms of a web application, a Controller takes the http request, the model contains all the information you need to present to the user and then the controller selects the view and view decides how to show this information.

aspnet-mvc-2

This isolation makes it easy to manage and update a web application.

ViewBag

ViewBag is a dynamically typed object in C# that means you can add any sort of property to it and it will be available inside of the view to pull out and retrieve and display.