This book aims to give readers a broad mathematical basis for modeling and understanding the wide range of wave phenomena encountered in modern applications, especially in gasdynamics. The material originated from a coarse that has been taught at Oxford University for many years. It is a development of Inviscid Fluid Flows, by H. Ockendon and A. B. Tayler (Springer, 1983), which has been retitled and completely rewritten to reflect current research interests. In particular, a more comprehensive collection of models is used to illustrate the underpinning mathematical methodologies. These methodologies have been expanded to include the basic ideas of hyperbolic differential equations, characteristics, ray theory, asymptotic analysis, dispersion, shock waves, and weak solutions. Although the main focus is on compressible fluid flow, the authors show how wave phenomena in other areas such as electromagnetism and solid mechanics can be treated using similar techniques. Special emphasis is placed on the development of physical intuition to supplement and reinforce analytical thinking. Each chapter includes a complete set of carefully prepared exercises, making this a suitable textbook for students in applied mathematics, engineering, and other physical sciences.