Windows is the plural form of window. It may also stand for: Computer Software Window (computing), a rectangular frame in a graphical user interface inside which a program runs. Microsoft Windows, a family of Microsoft operating systems since about 1985 X Window System, the Unix/Linux/BSD graphical user interface, also known as "X Windows". OpenWindows, a GUI for the Solaris Operating System from 1989 to about 2002 DECwindows, a version of the desktop environment Common Desktop Environmen… (More on Windows)