Microsoft Windows is a product line of proprietary graphical operating systems developed and marketed by Microsoft. It is grouped into families and sub-families that cater to particular sectors of the computing industry -- Windows (unqualified) for a consumer or corporate workstation, Windows Server for a server and Windows IoT for an embedded system. Defunct families include Windows 9x, Windows Mobile, Windows Phone, and Windows Embedded Compact.

MS-DOS is an operating system for x86-based personal computers mostly developed by Microsoft. Collectively, MS-DOS, its rebranding as IBM PC DOS, and a few operating systems attempting to be compatible with MS-DOS, are sometimes referred to as "DOS". MS-DOS was the main operating system for IBM PC compatibles during the 1980s, from which point it was gradually superseded by operating systems offering a graphical user interface (GUI), in various generations of the graphical Microsoft Windows operating system.