This paper discusses the evolution of military requirements, from a relatively simple scanned linear array of detectors, to a scanned two-dimensional array of detectors with time delay and integration, to two-dimensional staring arrays. We review the process that led to the concentration on one detector material, namely, mercury cadmium telluride, to satisfy most military requirements. The various material growth methods are described. These growth techniques are closely coupled to material characterization techniques, both as an analytical tool and for in-process control. Finally, we review focal plane array fabrication technology and the relationship between detector and on-focal-plane processing parameters.