This book, a collection of works by leading figures in the field, is devoted to the latest developments of modern magnetism including micromagnetism, nanomagnetism, materials, magnetic multilayers, macroscopic quantum magnetism, rare-earth intermetallic compounds, giant magnetoresistance, and their applications. Some new concepts and theories are also included for a better understanding of these novel phenomena. This book can be used as an advanced text book on magnetism and materials science for graduate students in physics and materials science departments. It is also useful as a research reference for condensed matter physicists and materials scientists.