Possible Duplicate:
How does facebook rewrite the source URL of a page in the browser address bar?
When I click on a photo in Facebook, it makes an AJAX request. Then, my browser changes its address bar from:
http://www.facebook.com/home.php
to:
http://www.facebook.com/photo.php?fbid=251545528207986&set=a.139901389372401.20498.100000576210972&type=1&theater
How does this happen? The page is the same; the only thing that changes is the address bar. Facebook also does not use hash marks (#!) like Twitter does; so then how can Facebook do that from an AJAX request?
