MVC paradigm. Why only application_controller?

Question

Rails uses the MVC paradigm. It's interesting in models, views, and controllers, really only controllers have an 'application' or parent controller. Actually there is an application_helper in rails but it really doesn't do much. What's the point of only have an application_controller where as models and in practice helpers do not have a parent?

Answer 1

Models have a parent, ActiveRecord::Base ApplicationController is there because its too common to see application wide filters that you need in a web app for authentication/authorization etc. The application helper, again is there to put helper methods that get used across the application, beyond the scope of just one controller.