I want to hide page extensions like stackoverflow does. How does the following work?
http://stackoverflow.com/tags/foo http://stackoverflow.com/tags/bar
That's the beauty and the work of ASP.NET MVC.
No "hiding" - it's just the way ASP.NET MVC handles URL's and maps those "routes" to controller actions on your controller classes.
Quite a big step away from the "classic" ASP.NET Webforms way of doing things.