What is a robot? We might define it most briefly and comprehensively as "an artificial object that resembles a human being." When we think of resemblance, we think of it, first, in terms of appearance. A robot looks like a human being. It could, for instance, be covered with a soft material that resembles human skin. It could have hair, and eyes, and a voice, and all the features and appurtenances of a human being, so that it would, as far as outward appearance is concerned, be indistinguishable from a human being. This, however, is not really essential. In fact, the robot, as it appears in science fiction, is almost always constructed of metal, and has only a stylized resemblance to a human being. Suppose, then, we forget about appearance and consider only what it can do. We think of robots as capable of performing tasks more rapidly or more efficiently than human beings. But in that case any machine is a robot. A sewing machine can sew faster than a human being, a pneumatic drill can penetrate a hard surface faster than an unaided human being can, a television set can detect and organize radio waves as we cannot, and so on. We must apply the term robot, then, to a machine that is more specialized than an ordinary device. A robot is a computerized machine that is capable of performing tasks