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), External Hosts, or Custom Web Servers. You can use any of these web servers with a file-based web application project. For a file-based web site project, you can use IIS Express. This topic describes each of the web servers and how to select a web server for testing.