In the middle and late 1960s, holography, applied to acoustics, generated a considerable upsurge of activity in the already mature acoustic imaging technology. It brought both coherent optics and digital data processing to bear upon the problems of acoustic imaging and introduced fresh approaches to the visualization of sound fields. These developments are reviewed and the wide range of potential applications for acoustic holography is discussed. In most cases, the status is that of proved feasibility awaiting broader application.