Hosting Process (vshost.exe)
VSHost.exe, the debugger hosting process in Visual Studio 2010, improves debugging performance, enables partial trust debugging, and enables design time expression evaluation. The hosting process files contain vshost in the file name and are placed in the output folder of your project. For more information, see Debugging and the Hosting Process.
Hosting process files (.vshost.exe) are for use by Visual Studio and should not be run directly or deployed with your application..
Visual Studio loads the hosting process when a solution is opened and performs certain actions, such as attaching the debugger to the host process and loading referenced modules. When you begin debugging, the hosting process loads only the modules created in your solution, significantly reducing the time it takes to run the application.
An application can be specified as a partial trust application in the Security page of the Project Designer. Debugging a partial trust application requires special initialization of the application domain. This initialization is handled by the hosting process.
Design-time expression evaluation enables you to test code from the Immediate window without having to run the application. The hosting process executes this code during design time expression evaluation. For more information, see Immediate Window.