title: How to create and use a module using Ruby on Rails 3?
body: <p>I am using Ruby on Rails 3 and I would like to move some custom and shared code in a module. </p>
  
  <ol>
  <li>What syntax should I use to write the module code? </li>
  <li>In which folder of my application I have to place the module file?</li>
  <li>How I have to include that module in one or more controller classes?</li>
  <li>What other action, if any, do I have to use the custom module anywhere in my application?</li>
  <li>How can I call methods in the module from my application?</li>
  </ol>
  
  <p>Thanks in advance.</p>