The basic building block of images on a computer screen is a dot of light called a pixel—the word created by combining the words "picture" and "element."

The computer, because it can present thousands of pixels on a computer screen in millions of different colors, can create shapes that the human eye recognizes as an image—a computer graphic.

It is hard now to imagine a world without computer graphics. Today's children have grown up with video games, and graphic designers work almost exclusively with computer programs to create images once laboriously drawn with pen, compass, ruler, and T-square on paper. Pilots learn the latest techniques of flying in flight simulators; engineers and architects design everything from aircraft to skyscrapers, making three-dimensional models with their computers; TV weather maps display precipitation as it occurs; and doctors can look inside a patient's body without breaking the...