Microsoft Windows is a group of graphical operating systems, all of which are developed, marketed, and sold by Microsoft. Some of the well-known client versions include Windows 98, ME, XP, Vista, and 7. Windows 10 is the most recent version. Server versions include Windows NT Server, 2000 Server, 2003 Server, and Server 2008 R2. Windows Server 2016 is the most recent server version.