title: What is the meaning of the keyword "do", in ruby?
body: <p>I've seen a couple of <code>do</code> in Ruby, and I couldn't find a really good explanation of its purpose. For example, a place where I saw a <code>do</code> was in the <code>gemfile</code>:</p>
  
  <pre><code>group :development, :test do
      gem 'rspec-rails'
      gem 'rspec-its'
      gem 'simplecov', :require =&gt; false
      gem 'guard-rspec'
      gem 'spork-rails'
      gem 'guard-spork'
      gem 'childprosess'
      gem 'rails-erd'
      gem 'pry-rails'
      gem 'guard-rails'
      gem 'guard-livereload'
      gem 'guard-bundler'
  end
  </code></pre>
  
  <p>I know what this code does, but I don't know the purpose of <code>do</code>. I have my guesses, but I want them confirmed or denied by someone who knows more than me.</p>