Ruby puts the Ruby in “Ruby on Rails”! It’s the Ruby language that makes Rails flexible, powerful, and with a developer-friendly API. How does Rails take advantage of Ruby’s flexibility and metaprogramming to make it so useful? And how can you take advantage of those features in your Rails app? We’ll go over a few specific Ruby features, like how Rails uses Modules, or `define_method` or `instance_eval`. You’ll be able to use these features to make your app as powerful as Rails itself. Ruby Central