Internet Information Services (IIS) needn't be installed for developing Web applications with Visual Studio 2005 because Studio 2005 has its own Web server: the Visual Web Developer Web Server. This is a simple Web server that runs only on the local machine. On the production system, IIS is needed to run the Web application.
Now look at how IIS and ASP.NET fit together. Figure 21-1 shows Windows XP's process model. IIS is running in the inetinfo.exe process. This process has an ISAPI extension for ASP.NET that uses configured file extensions to pass requests from the client to the ASP.NET process aspnet_wp.exe. By default, IIS's processes run with System account privileges, while the ASP.NET runtime runs with the nonprivileged user aspnet.
Figure 21-1