In this paper we trace the development of measurements of ECE on fusion machines from the early days, when the main interest in this emission was its contribution to the power loss, to the present, where such measurements are employed as a powerful diagnostic of the plasmas produced in most contemporary tokamak and stellerator machines. The development path has not always been smooth but it has always been rich in creativity, surprises, debate and ultimately success. The significant developments in the field are identified and illustrated with examples.