Beyond icons: surface and structure of user interfaces

The concept of a user interface includes the complex of command languages, operations, design principles, and standards associated with the increasingly important and wide-spread use of interactive systems. Technological innovations, mostly in hardware but some in software, have been the driving forces. These include: time-sharing, workstations with bitmap graphics, graphic input devices, efficient multiprocessing, and multimegabyte memories for personal computers. Techniques of interaction followed, with operating systems that support user interaction, menus and icons, window systems, graphic interaction techniques such as snap-dragging, and integrated systems where all interactive applications share certain universal operations. Design principles are emerging, but standards remain a task for the future