> 
> **Possible Duplicate:**  
> 
> [What's the shebang (#!) in Facebook and new Twitter URLs for?](https://stackoverflow.com/questions/3009380/whats-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 ?