Water and air produce many kinds of flow. For example, the flow in a stream, the wind around a towerblock and the turbulence around an airplane. This book was edited with two goals; one is to show the very close relationship between fluid flow and our life and the other is to introduce the form and beauty of fluid flow. Recently, great progress has been made in flow visualization techniques. As the proverb says 'Seeing is believing', seeing is the best way to understand the phenomena of flow. The full color pictures of this book will initiate the readers' interest in the beauty of flow and encourage them to discover more about the fluid flow around themselves.