Dictionary.net

Interface, point-of-contact software managing what passes forth and back between the computer and its user. Whatever displays, whatever a user enters, by keystroke, mouseclick, finger or stylus touch, or speech, is managed and controlled by the GUI. Xerox pioneered it and Apple deployed it in its computers. GUI is now used in every operating system by most application programs. The GUI uses graphic elements like dialog boxes, icons, menus, scroll bars, more so than text characters to let the user enter commands and do on-screen manipulations. A GUI is built to use a consistent set of graphical elements. Once the user learns a particular interface, similar programs become usable without additional learning.