Application Web Servers

    When you develop Web projects in Visual Studio, you need a Web server to test or run them. Visual Studio lets you test with different Web servers, including IIS Express, Internet Information Services (IIS), or the built-in Visual Studio Development Server. You can use any of these servers with a file-based Web application project. For a file-based Web site project, you can use IIS Express or the built-in Visual Studio Development Server.

Ø  The following table provides summary guidance for choosing a Web server in Visual Web Developer.

Web server	When to use
IIS Express	Use when the target Web server is IIS 7 but you do not want to (or cannot) use the full version of IIS 7. This requires Visual Studio 2010 Service Pack 1, and IIS Express must be installed separately. IIS Express hosts sites in a manner that is very similar to IIS 7.
Visual Studio Development Server	Use when you are working with an existing project or your site targets an older version of IIS, such as IIS 6, and it is not very important that your testing environment match the production environment closely. This server option is the default in Visual Studio. However, the Visual Studio Development Server runs in a different security context than full IIS, and may fail to reveal errors that can occur when you deploy to a production version of IIS.
IIS	Use when you want to test your Web application using the server environment that is closest to what the live site will run under, and it is practical for you to install and work with IIS on your development computer. However, it can be more complex to configure debugging and other tasks than if you use IIS Express or the Visual Studio Development Environment. Requires you to run Visual Studio as an administrator.