title: ruby gems vs rails gems
body: <p>Sorry if this is a newbie question but what exactly is the difference between the gem structure of a Ruby gem vs. Rails gem.</p>
  
  <p>Strictly speaking, all Rails gems are also Ruby gems, but not the other way around.  So what additional files are required to make a ruby gem into a Rails gem.</p>
  
  <p>For example, in this post, <a href="https://stackoverflow.com/questions/2072059/building-a-ruby-gem-for-rails-applications">Building a ruby gem for Rails applications</a>, the top answer suggests that all Rails gems need an init.rb.  But then I found some rails gems that don't have the init.rb file.  Here is an example: <a href="https://github.com/collectiveidea/awesome_nested_set" rel="nofollow noreferrer">https://github.com/collectiveidea/awesome_nested_set</a></p>
  
  <p>Basically, I want to write a Rails gem.  I find a lot of tutorials on writing Ruby gems, but I just want to make sure it works for a Rails app.</p>