Closing Applications

System.Windows.Forms.Application.Exit() - Informs all message pumps that they must terminate, and then closes all application windows after the messages have been processed. This method stops all running message loops on all threads and closes all windows of the application. This method does not force the application to exit. The Exit() method is typically called from within a message loop, and forces Run() to return. To exit a message loop for the current thread only, call ExitThread(). This is the call to use if you are running a Windows Forms application. As a general guideline, use this call if you have called System.Windows.Forms.Application.Run().

System.Environment.Exit(exitCode) - Terminates this process and gives the underlying operating system the specified exit code. This call requires that you have SecurityPermissionFlag.UnmanagedCode permissions. If you do not, a SecurityException error occurs. This is the call to use if you are running a console application.

I hope it is best to use Application.Exit

See also these links:

• Application.Exit() vs Application.ExitThread() vs Environment.Exit()
• http://geekswithblogs.net/mtreadwell/archive/2004/06/06/6123.aspx

Application.Exit is for Windows Forms applications - it informs all message pumps that they should terminate, waits for them to finish processing events and then terminates the application. Note that it doesn't necessarily force the application to exit.

Environment.Exit is applicable for all Windows applications, however it is mainly intended for use in console applications. It immediately terminates the process with the given exit code.

In general you should use Application.Exit in Windows Forms applications and Environment.Exit in console applications, (although I prefer to let the Main method / entry point run to completion rather than call Environment.Exit in console applications).

For more detail see the MSDN documentation.