title: Helpers in Rails 4
body: <p>I make an application writed in Rails, it's growing fast and I learning with it. But I'm don't understand about helpers.</p>
  
  <p>application_helper.rb</p>
  
  <pre><code>module ApplicationHelper
      # This file it's empty
  end
  </code></pre>
  
  <p>users_helper.rb</p>
  
  <pre><code>module UsersHelper
  
      def avatar
          # Do something
      end
  end
  </code></pre>
  
  <p>customer_helper.rb</p>
  
  <pre><code>module CustomerHelper
      # This file it's empty
  end
  </code></pre>
  
  <p>Why in any customer's view can call avatar helper method on user helper module?
  Then, why separate helpers in many files?</p>
  
  <p>Thanks in advance.</p>
  
  <p>P.S: Rails' version 4.</p>