'''Windows on Windows''', commonly referedreferred 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-bit_Edition|Windows XP 64]] versions of Windows requires a whole new Wow called Wow64.