Why exclamation is used in URLs?
url
Solution
It's because it is an AJAX crawlable notation for URLS, an effort driven by Google to define a convention allowing Web 2.0 websites to be indexed by search engines.
And of course check the perfectly valid answer for What's the Shebang in the new Facebook and Twitter URLs?
Problem
Possible Duplicate: What's the shebang (#!) in Facebook and new Twitter URLs for? Hi I was just wondering what is the use of "!" in urls like this `http://www.facebook.com/profile.php?id=xxxxxxxx&v=wall#!/profile.php?id=yyyyyy&v=wall` I know Facebook uses #(hash) for changing the query string parameters with JavaScript but what is the meaning of exclamation (!), why it is used after # ? We can even work with # only to change the querystring params. Is there any benefit of using ! ? or any other thing is there which I am missing ?