This long-awaited graduate textbook, written by two pioneers in the field, provides a comprehensive introduction to the observations, theories, and consequences of stellar winds. The rates of mass loss and the wind velocities are explained from basic physical principles. This textbook also includes chapters clearly explaining the formation and evolution of interstellar bubbles and the effects of mass loss on the evolution of high- and low-mass stars. Each topic is introduced simply to explain the basic processes and then developed to provide a solid foundation for understanding current research. This authoritative textbook is designed for advanced undergraduate and graduate students and researchers seeking an understanding of stellar winds and, more generally, supersonic flows from astrophysical objects. It is based on courses taught in Europe and the United States over the past twenty years and includes seventy problems for coursework or self-study.