The first textbook on Bose-Einstein correlations and their applications, an interdisciplinary topic bridging particle physics and quantum physics, and currently the centre of considerable interest in high energy physics. Besides its fundamental importance for particle physics, this phenomenon constitutes the main tool for the determination of sizes and lifetimes of particle sources. The contents of this book are divided into the following chapters, each of which concludes with exercises designed to test the reader's understanding of the concepts and theories included therein: The Foundations; Hadron Interferometry; Currents; Sources; Applications to Ultrarelativistic Nucleus-Nucleus Collisions; Correlations and Multiplicity Distributions; Photos versus Hadrons. It provides the first systematic analysis and comparison of the different theoretical approaches to the subject and will be invaluable to theorists and experimentalists in particle and nuclear physics, quantum optics and astrophysics.