The first generation of experimental time-sharing systems are currently in operation. They leave much to be desired in terms of generality, efficiency, and availability. They are not perfect, but they do work. They have had a beneficial influence on the design of both totally new products and of optional features appearing in modern equipment. Several new programming techniques have also proven their value. The people using time-sharing have contributed much: the users with their enthusiastic acceptance of this mode of operation, and the programmers who are eager to write new systems that can efficiently utilize generalized time-sharing techniques.