A description of the inertial technology used for guidance, control, and navigation, discussing in detail the principles, operation, and design of sensors, gyroscopes, and accelerometers, as well as the advantages and disadvantages of particular systems. An engineer with long practical experience in the field, the author elucidates such recent developments as fibre-optic gyroscopes, solid-state accelerometers, and the global positioning system. This will be of interest to researchers and practising engineers involved in systems engineering, aeronautics, space research, and navigation on both land and sea.