title: How does facebook rewrite the source URL of a page in the browser address bar?
body: <p>Go to <a href="http://www.facebook.com/facebook?v=wall">http://www.facebook.com/facebook?v=wall</a>, then click on the info tab. The content will be loaded, and the address bar now becomes <a href="http://www.facebook.com/facebook?v=info">http://www.facebook.com/facebook?v=info</a> but the webpage didn't reload.</p>
  
  <p>At first I think it is Ajax, but my question is, how do you change the address bar without reloading? I know I can change anchor (#wall) using JS but querystring (?v=wall), how?</p>