Ivan Sutherland - Sketchpad, A Man-Machine Graphical Communication System (1963)

Sketchpad (aka Robot Draftsman) was a revolutionary computer program written by Ivan Sutherland in 1963 in the course of his PhD thesis, for which he received the Turing Award in 1988. It helped change the way people interact with computers. Sketchpad is considered to be the ancestor of modern computer-aided drafting (CAD) programs as well as a major breakthrough in the development of computer graphics in general. For example, the Graphic User Interface was derived from the Sketchpad as well as modern object oriented programming. Ivan Sutherland demonstrated with it that computer graphics could be used for both artistic and technical purposes in addition to showing a novel method of human-computer interaction. From the Wikipedia entry, read more HERE.