Windows NT

From Rosetta Code

Windows NT is the current line of Windows operating systems developed by Microsoft. This includes:

...and most likely future versions of Windows as well.

Windows NT does not include Windows 9x/Me or Windows 3.x or older, none of which were actual operating systems, but rather graphical shells that ran on top of DOS. (Windows NT was developed from the original OS/2 codebase after Microsoft and IBM parted ways.)

ReactOS is an open-source implementation of Windows NT, specifically aimed at binary compatibility with Windows Server 2003 (NT 5.2). It is not a Microsoft product, and isn't included in any official list of Windows versions. It also isn't ready for public use, having been in alpha status for several years.

For more information, including a more inclusive list of NT versions, see Wikipedia's Windows NT entry.