Windows is the operating system that comes on almost every PC. At first, Windows was more of a GUI for MicroSoft's DosOs, but is now their flagship OS. Various versions of Windows include: Windows 3.1, Windows 95, Windows 98, Windows NT, Windows 2000, Windows ME, with the latest version being Windows XP.
Information about programming in Windows (Win32) can be found in the [^http://msdn.microsoft.com Microsoft Developer Network (MSDN)].
Bits on the Win32API in Win32ApiProgramming.