The common language runtime has been designed to support a variety of different types of applications, from Web server applications to applications with a traditional rich Windows user interface. Each type of application requires a runtime host to start it. The runtime host loads the runtime into a process, creates the application domains within the process, and loads user code into the application domains.
The .NET Framework ships with a number of different runtime hosts, including the hosts listed in the following table.
Loads the runtime into the process that is to handle the Web request. ASP.NET also creates an application domain for each Web application that will run on a Web server.
Microsoft Internet Explorer
Creates application domains in which to run managed controls. The .NET Framework supports the download and execution of browser-based controls. The runtime interfaces with the extensibility mechanism of Microsoft Internet Explorer through a mime filter to create application domains in which to run the managed controls. By default, one application domain is created for each Web site.
Invokes runtime hosting code to transfer control to the runtime each time an executable is launched from the shell.
Microsoft provides a set of APIs for writing your own runtime hosts.