Covering basic physical concepts, experimental methods, and applications, this book is an indispensable text on the fascinating science of magnetism, and an invaluable source of practical reference data. Accessible, authoritative, and assuming undergraduate familiarity with quantum mechanics, electromagnetism and vectors, this textbook can be used on graduate courses. Emphasis is placed on practical calculations and numerical magnitudes - from nanoscale to astronomical scale - with a focus on modern manifestations, including spin electronic devices. Each self-contained chapter begins with a summary, and ends with exercises and further reading. The book is thoroughly illustrated with over 600 figures to help convey concepts and clearly explain ideas. Easily digestible tables and data sheets provide a wealth of useful information on magnetic materials, and 38 principal magnetic materials, and many more related compounds, are treated in detail.