A computer interface (i.e., the means by which the user and the computer communicate with each other) which uses visual, graphical icons, windows, pull-down menus, and a pointing-clicking-dragging device (such as a mouse) to manipulate screen objects, rather than relying on a straight, somewhat cryptic and technical text, to convey messages and accept commands. Early personal computers used BASIC, DOS, UNIX, or some other text-based interface, called a command-line interface, which consisted of sometimes obscure commands and proper syntax to locate, open, save, and copy files and programs, or perform any other computer function. The GUI was first developed by Xerox at the Palo Alto Research Center (PARC) in the early- to mid-1970s. The first true GUI-based personal computer was the early Apple Lisa and, shortly thereafter, the Macintosh. Microsoft Windows is a GUI that is merely a layer of user-friendliness sitting on top of the DOS infrastructure.
With a GUI (pronounced "GOO-ee"), files are represented on the screen (which is designed to look like—and is called—a desktop) as pieces of paper, and directories are represented as folders. A feature unique to GUIs is their reliance on a mouse, or other type of pointing device, to move objects around the screen and "click" on files to open them. It could be argued that the GUI was responsible for the proliferation of personal computers in the 1990s. A GUI, relying as it does on the use of icons, is sometimes called an iconic interface.