Rails application.html.erb?

The old Rails used to have an application.rhtml file. The newer version appear to have .html.erb files for each model. What's the reason there is currently no application.html.erb file?

From stackoverflow

• You can create an application.html.erb file in the app/view/layouts directory if you want to have an application-wide layout file.

  Daniel : Sweet, thanks John.

• And what did the old application.html.erb file show? One of your models? So why not make it a model.html.erb file?