window system

A windowing system (or window system) is a graphical user interface (GUI) which implements windows as one of its primary metaphors. It is normally one part of a larger desktop environment.From a programmer's point of view, a windowing system implements graphical primitives such as rendering fonts or drawing a line on the screen, effectively providing an abstraction of the graphics hardware.A windowing system enables the computer user to work with several programs at the same time. Each program runs in its own window, which is an area of the screen, typically a rectangle. Most windowing systems allow windows to overlap, and provide means for the user to perform standard operations such as moving/resizing a window, sending a window to the foreground/background and minimizing/maximizing a window.
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Software which allows a workstation's screen to be divided into rectangular areas which act like a separate input/output devices under the control of different application programs. This gives the user the ability to see the output of several processes at once and to choose which one will receive input by selecting its window, usually by pointing at it with a mouse.
Examples are the X Window System, and proprietary systems on the Macintosh and NeXT, NeWS on Suns and RISC OS on the Archimedes. See also WIMP.