This book provides a solid introduction to the classical and statistical theories of thermodynamics while assuming no background beyond general physics and advanced calculus. Though an acquaintance with probability and statistics is helpful, it is not necessary. Providing a thorough, yet concise treatment of the phenomenological basis of thermal physics followed by a presentation of the statistical theory, this book presupposes no exposure to statistics or quantum mechanics. It covers several important topics, including a mathematically sound presentation of classical thermodynamics; the kinetic theory of gases including transport processes; and thorough, modern treatment of the thermodynamics of magnetism. It includes up-to-date examples of applications of the statistical theory, such as Bose-Einstein condensation, population inversions, and white dwarf stars. And, it also includes a chapter on the connection between thermodynamics and information theory. Standard International units are used throughout. An important reference book for every professional whose work requires and understanding of thermodynamics: from engineers to industrial designers.