Today, software can turn a computer into a television, record player, or paintbox and canvas or make it transmit telephone conversations, edit and replay video images and music, snap family photos, synthesize human speech, imitate a 16th century harpsichord, organize databases and libraries full of books, and coordinate activities across space and time. Using real or imagined data, the computer can simulate complex physical and logical processes or entire ``chunks of reality and make them ``real through a combination of animated drawings, sounds, and even tactile feedback.