The paper identifies the essential features of tracking systems and describes the basic ranging facilities that were available during the early years of the Second World War on the metric radar systems. With the advent of centimetric radar and the development of both low- and high-angle systems, tracking in range elevation and bearing was realised. In the discussion of the following two decades, with the emphasis on radioastronomy and satellite communication and the requirement for large apertures, the Jodrell Bank Mk. I and the Goonhilly I systems are considered and the transition from analogue to computer control noted. The need for fast scanning, realised by monopulse techniques, is then examined and reference is also made to the application of ‘hill-climbing’ techniques. The paper continues with an account of missile tracking strategies and the significance of the guidance law. In the final Section the problems arising from system disturbances are discussed, and recent work based on Kalman filtering is mentioned in that context. In conclusion it is noted that the development of tracking systems has been sustained by the progress and integration of the computing and control disciplines.