This comprehensive and extensively classroom-tested biophysics textbook is a complete introduction to the physical principles underlying biological processes and their applications to the life sciences and medicine. The foundations of natural processes are placed on a firm footing before showing how their consequences can be explored in a wide range of biosystems. The goal is to develop the readers' intuition, understanding, and facility for creative analysis that are frequently required to grapple with problems involving complex living organisms. Topics cover all scales, encompassing the application of statics, fluid dynamics, acoustics, electromagnetism, light, radiation physics, thermodynamics, statistical physics, quantum biophysics, and theories of information, ordering, and evolutionary optimization to biological processes and bio-relevant technological implementations. Sound modeling principles are emphasized throughout, placing all the concepts within a rigorous framework. With numerous worked examples and exercises to test and enhance the reader's understanding, this book can be used as a textbook for physics graduate students and as a supplementary text for a range of premedical, biomedical, and biophysics courses at the undergraduate and graduate levels. It will also be a useful reference for biologists, physicists, medical researchers, and medical device engineers who want to work from first principles.