Many times there is requirement for SharePoint 2010 public facing site to use short url. Like http://example.com/BussinessBanking instead of http://example.com/Pages/BussinessBanking.aspx
URL Rewrite is a URLs management component for IIS7. Although it’s called URL Rewrite but it allows you to create and manage both URL rewrites and redirects. Probably the best thing about the URL Rewrite 2.0 is that it’s a solution provided and supported by Microsoft that fully integrates with IIS7
Here is a good article for url rewrite
For url rewriting your site must have anonymous access, it will not work for authentication environment.