An introductory survey of the gyroscope is provided, starting with relatively simple concepts and applications to missile technology and proceeding through to a few of the more involved characteristics of the device. In ballistic and other missiles, gyroscopes may contribute to two basic functions. One is control of the missile, and the other is possible inertial guidance of the missile. For a missile, the problem of control includes provision of the means for i minimizing the undesirable effects of wind, gusts, and other disturbances on the missile assembly and ii maintaining stability of missile when overriding guidance signals are introduced. The problem of guidance, on the other hand, is to provide means for generating the overriding signals that will enable the missile ultimately to hit the selected target.