Graphical user interface
A graphical user interface (or GUI, pronounced "gooey") is a human-computer interaction method that uses graphical images in addition to text. If you are using a computer to view this article, you are probably using one right now.
The graphical user interface was invented at Xerox PARC and most modern GUIs are derived from it. For this reason, some people call this class of interface a PARC User Interface (PUI). The PUI consists of widgets such as windows, menus, buttons, radio boxes, and icons, and employs a pointing device (such as mouse, trackball, or touchscreen) in addition to a keyboard. For this reason, many people refer to PUIs as WIMPs (Windows, Icons, Mouse, Pointer).
Examples of systems that support PUIs are Mac OS, Microsoft Windows, and the X Window System. The latter is extended with toolkits such as KDE and GNOME.
GUIs that are not PUIs are most notable in computer games. Advanced GUIs based on virtual reality are frequent in research.
Similar to GUIs are text user interfaces (TUIs) that display the same types of widgets in a character-cell mode rather than in a pixel mode.
Examples include the interfaces of many ncurses and MS-DOS applications.
The graphical user interface is generally contrasted with the command line interface. Because GUIs and TUIs tend to show most or all relevant categories of commands on the display, users often learn them faster than CLIs, but users with vision or motion disability often have trouble navigating in a GUI, and most commercial GUIs use at least an order of magnitude more computer power than a CLI, making a GUI unwieldy on older hardware.
See also History of the GUI, human-computer interaction, UIML, Fitts' law