title: What is %2 in $id%2
body: <p>What does %2 do in the following php?</p>
  
  <pre><code>$id=(int)@$_REQUEST['id'];
  echo ( !($id%2) )?
      "{'id':$id,'success':1}":
      "{'id':$id,'success':0,'error':'Could not delete subscriber'}";
  </code></pre>