According to Wikipedia, Web server is a computer program that is responsible for accepting HTTP requests from clients, which are known as Web browsers, and serving them HTTP responses along with optional data contents, which usually are Web pages such as HTML documents and linked objects (images, etc.). An application server is a software engine that delivers applications to client computers or devices. Moreover, an application server handles most, if not all, of the business logic and data access of the application (a.k.a centralization).

IIS is a web server which sits on the top of the ASP.NET engine to make it look like an Application server. However, IIS can only deal with HTTP responses. Hence, it is a web server. In this article let us try to explore IIS as a web server. Also, let us try to understand how the IIS 6.0 is coupled with ASP.NET runtime.