Windowing System Definition

A windowing system, also referred to as a window system, is a collection of software that creates the basic GUI (graphical user interface) on computer display screens, including the drawing of windows and other graphics primitives (i.e., basic shapes) for application programs.

A GUI is a type of human-computer interface that uses windows, icons (i.e., small images), pull-down menus and a pointer and that can be manipulated by a mouse (and usually to some extent by a keyboard as well). A window is a (usually) rectangular portion of the display on a computer monitor that presents its contents (e.g., the contents of a directory, a text file or an image) seemingly independently of the rest of the display screen, including other windows on the screen.

The X Window System, often referred to merely as X, is a complete, cross-platform and free windowing system for managing GUIs on single computers and on networks of computers. It is one of the most powerful and useful software packages for Linux and other Unix-like operating systems, and it is the de facto standard windowing system for such operating systems. Other windowing systems have been developed for Unix-like operating systems, such as Y Window System, but generally are not widely used.

Some operating systems use windowing systems that are integral parts of the operating system, such as the various Microsoft Windows systems and Mac OS 9 and earlier. Apple Computer's development of the Quartz Compositor windowing system for the Mac OS X has been a major factor in the outstanding performance and growing popularity of OS X.

The relatively small number of high quality windowing systems available, and their slow evolution, is largely a result of the extremely complex nature of such systems and the consequent difficulty in developing them. For example, it is said that the X Window System has an order of complexity as great as that of an operating system itself.

The term graphic engine is sometimes used as a synonym for windowing system. However, it can also refer to a layer of software that is used by specific application programs, or groups thereof, on top of the windowing system rather than the basic windowing system itself. For example, many games that operate on the Microsoft Windows systems employ special, high-performance graphic engines that are used on top of the Microsoft Windows windowing system.

Created December 17, 2005.
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