4.2 Say "Hello", Rails

To get Rails saying "Hello", you need to create at minimum a controller
and a view.

A controller's purpose is to receive specific requests for the
application. Routing decides which controller receives which requests.
Often, there is more than one route to each controller, and different
routes can be served by different actions. Each action's purpose is to
collect information to provide it to a view.

A view's purpose is to display this information in a human readable
format. An important distinction to make is that it is the controller,
not the view, where information is collected. The view should just
display that information. By default, view templates are written in a
language called ERB (Embedded Ruby) which is converted by the request
cycle in Rails before being sent to the user.

To create a new controller, you will need to run the "controller"
generator and tell it you want a controller called "welcome" with an
action called "index", just like this:
$ rails generate controller welcome index