On some .NET driven sites URLs don't end with asp.net page names, like default.aspx, instead they use a pattern http://sitename.com or http://sitename.com/subdirectory/subdirectory. The site is mapped as sub directories off the root, ie. /tags, /users, /badges, the URLs would be /tags, /users, /badges respectively.
Stack Overflow, to use a specific example, uses question URLs of the form How do get clean URLs like Stackoverflow?. Which is great way to optimize the page for search engines.
Is this implemented using HTTP handlers? Is the GET request filtered based on path and the whole response is formed in the handler itself based on the question id? Anyone else care to speculate?
It's ASP.Net MVC, which has the .Net Routing more or less built in. The Routing is available for non MVC projects as well, though
http://msdn.microsoft.com/en-us/library/cc668201.aspx
It's just a .dll you can drop in your bin folder. Basically it uses regular expressions to match your URL's to pages/templates.