James Lighthill provides readers with a thorough analysis of sound waves, shock waves, waterwaves of all kinds, and the so called internal waves (inside atmospheres and oceans) due to intensity stratification. He emphasizes the most useful fundamental ideas of wave science, including the principles of how waves interact with flows. This work on one of the great subdivisions of fluid dynamics will be invaluable to engineers, physicists, geophysicists, applied mathematicians, and researchers concerned with wave motions or fluid flows.