If you're used ASP.NET MVC or ASP.NET Dynamic Data, you've using ASP.NET's new Routing feature. ASP.NET Routing is the feature that lets you easily create so-called "pretty" URLs. Pretty URLs are the ones that look the way you want them to look (e.g. ~/products/beverages), not the way your web application platform forces them to look (e.g. ~/products.aspx?categoryname=beverages).