The Xerox Star was an early commercial computer introduced in 1981. It was the first computer mimicking the office paradigm to make computer operation more easy for people by using icons representing familiar office objects like the „document“ icon, folder icon and a two-button mouse, many of them later have become standard in personal desktop computers, like in 1983 the Apple Lisa did. Before, in 1973 the Xerox Alto introduced the first graphical user interface ever.
The Evolution of the document icon shape in Xerox Star.
Image: Wikipeda