IIS 7.0

Windows Server® 2008 featuring Internet Information Services 7.0 is a powerful Web application and services platform that delivers rich Web-based experiences. It offers improved administration and diagnostic tools to help achieve lower infrastructure costs on a variety of popular development platforms. With improved reliability and scalability, IT professionals and developers can manage the most demanding Web serving environments, from a single Web server to a large Web farm. 

http://learn.iis.net/page.aspx/101/introduction-to-iis7-architecture/