title: What does "ei" mean in the Google homepage url https://www.google.co.in/?gws_rd=cr&ei=xgH...?
body: <p>I know about some of the parameters in a google url, such as:</p>
  
  <ul>
  <li><code>gws</code> =google web server</li>
  <li><code>rd</code> = redirected </li>
  <li><code>cr</code> = country reffered </li>
  </ul>
  
  <p>But I noticed one I cannot identify: <code>&amp;ei=</code>. What does the <code>ei</code> mean in this URL?</p>
  
  <pre><code>http://www.google.co.in/url?ei=qWwlUqD4MIrRrQfD9ICIDw&amp;...etc...
  </code></pre>