Having once failed a student on a doctoral oral exam because he could not define flow around a basic structural shape, I required students in a hydrodynamics course to obtain this book after it became available. Sometimes called "the picture book," it is an excellent reference illustrating all types of flow including creeping flow, laminar flow, separation, vortices, instability, turbulence, free-surface flow, natural convection, subsonic flow, shock waves, and supersonic flow. The author has researched the subject of flow visualization, and has acquired illustrations from a wide variety of sources. I was pleased to see that the book is still in print as it is a very valuable reference. The author has maintained a relatively low price to make it affordable to students.