Definition(en): Windows NT is a proprietary operating system produced by Microsoft, the first version of which was released on July 27, 1993. The first version of Windows NT was Windows NT 3.1 and was produced for workstations and server computers. It was a commercially focused operating system intended to complement consumer versions of Windows. Gradually, the Windows NT family was expanded into Microsoft's general-purpose operating system product line for all personal computers, and Windows NT depreciated.