(In ASP.net)
Separation of concerns. Model does data stuff. View is presentation. Controller plumbs data from the models and views.
MVC Pizza
Mark, Vinnie, Carmella.
Carmella (the controller) recieves phone orders. Tells Mark (the model) to make it. He gives is to her and she passes it on to Vinnie (the view) to delivers it to the user.
DetailsÖ
Lots of rather thin metaphores for invariant interfaces allowing you to modify/replace specific components.
Looks heaps like an ASP clone of Rails/CakePHP/etc.
Has standard routing of URLs to controller/action.
Built-in unit testing support, etc.