American computer scientist who helped develop a number of commonly used computer features, notably the graphical user interface (GUI) system. While working at the Xerox Palo Alto Research Center (PARC), Kay helped design GUI, the user-friendly graphics interface that utilized a "mouse" to point to "icons" and "windows" on the screen. This system became the standard graphical interface adopted by Macintosh and the Windows 95, 98, and NT operating systems. Kay also made important contributions toward developing the first laptop computer, and was primarily responsible for the Smalltalk computer language, an early object-oriented programming language.