If you launch an EXE created with Any CPU on a 64 bit machine the app will run 64 bit, and will run 32 bit on a 32 bit platform of Windows. What Any CPU does is essentially build your binary so it can execute either in 64 bit or 32 bit. If you're like most developers these days, when you build a Windows desktop or Console application you most likely use the default Any CPU target in Visual Studio to build your application:
