title: What is a Contract Class and how is it used
body: <p>In the recently updated Android Dev Guide, the documentation for Content Providers contains a section titled <a href="http://developer.android.com/guide/topics/providers/content-provider-basics.html#ContractClasses">Contract Classes</a>. Though there is a link to an example for Contacts, it was not immediately clear what is a Contract Class and how do I create one for my custom Content Provider   </p>
  
  <p>Would appreciate some help on this.</p>
  
  <p>Thanks!</p>