This book provides a solid pedagogical background in the techniques used in quantum optics, with an emphasis on open quantum systems. Suitable for undergraduates as a second semester quantum mechanics course or first-year graduate students, this book begins with a short summary of quantum mechanics and contains physics of open systems and their application to light/matter interactions. Written in a simplified manner and classroom tested, this book provides the fundamentals of quantum optics and includes recent developments in the field. Key Features Solid introduction to the key features of the field Excellent first exposure to nonequilibrium quantum statistical mechanics Developed from 30 years of teaching Includes recent developments in the field