i mean like this http://www.domain.com/cat.asp?health&id=21 instead http://www.domain.com/cat/health.html like in browser mean address bar
ASP doesn't support URL rewriting as far as I'm aware. You need PHP for that, also possible though more akward in ASP.Net.
ASP and ASP.Net does support URL rewriting through http modules and other methods. For asp.net you can try urlrewriter.net which is very simple to use and works in a shared hosting environment. However do remember that url rewriting is now not recommended by google as it does have some negative side effects
That's OK providing you have a dedicated web server, but many people simply use a hosting company who don't allow you to configure settings in IIS. PHP allows URL rewriting regardless, ASP doesn't.