title: What is the difference between service, directive and module?
body: <p>I have been reading a lot of docs, and I'm getting more and more confused.
  I basically can't figure out the difference between a </p>
  
  <ul>
  <li>service</li>
  <li>directive </li>
  <li>module</li>
  </ul>
  
  <p>I see a lot of custom components. Sometimes they're using directives, sometimes services. It always starts with a module. Can someone explain with an example what the difference is between these three types?</p>