It’s great being able to display information when your application starts, but typically you’ll want to enhance Rails applications in more interesting and useful ways than that. Most commonly, you’ll want to make one or more methods or classes available to the rest of your application.
The two defining aspects of a plugin are the presence of the
init.rb file and of a directory in the plugin called
lib. If neither of these exists, then Rails will not recognize the subdirectory of
vendor/plugins as a plugin. ...