Windows on Windows

Windows on Windows, commonly referred to as Wow, is an abstraction component of Microsoft Windows operating system. Wow is a critical component for backwards compatability of legacy code as Windows progresses. The first Wow appeared in Windows NT to support applications using the Win16 API. A less robust, but more compatible, version of Wow was used in Windows 95. Supporting Win32 applications on Windows XP 64 versions of Windows requires a whole new Wow called WoW64.