This article is about the graphical display of the functions of a computer in a viewport. For the data transmission period, see computer networking.

A window is a graphic, usually rectangular in shape, containing either some kind of graphical interface, or a textual representation, of the output of and allowing input for one of a number of simultaneously running computer processes.

Windows are primarily associated with graphical displays where they can be manipulated with a pointer, e.g. mouse, stylus or touchpad, however many plain text user interfaces allow their display to be divided into areas referred to as windows. Size and position can normally be adjusted, for example covering the whole screen, or half the screen, allowing another non-overlapping window using the other half, etc.

In graphical user interfaces windows are suggested to be objects (like papers or books) on a desktop: when two overlap, one is on top of the other, with the overlapping part of the lower window not shown; when moving, minimizing, resizing, or closing the upper window, hidden parts of the lower window reappear.

Windows are a popular feature (or widget) in several graphical user interfaces (especially WIMP ones). DEC Windows (for VMS), X Window System (for GNU & Unix-like systems), Microsoft Windows and IBM's Open Windows are named after this feature.

The ability to display and manipulate windows in a graphical display is provided by a windowing system (or windows system).

See also

• WIMP
• GUI
• Windowing system
• Window manager
• Desktop environment