What is Windows operating system?

     As of my last knowledge update in September 2021, Windows is a family of operating systems developed by Microsoft. Windows operating systems are widely used on personal computers, laptops, servers, and various other computing devices. Some of the well-known versions of Windows include:

Windows 3.1

Windows 95

Windows 98

Windows ME (Millennium Edition)

Windows 2000

Windows XP

Windows Vista

Windows 7

Windows 8

Windows 8.1

Windows 10

    Please note that since my knowledge is not up to date, there may have been new releases of Windows or changes to the Windows operating system beyond September 2021. You should check the official Microsoft website or other reliable sources for the most current information on Windows operating systems.