Magnetism in surfaces, heterostructures, small particles, and layered compounds has become an important subject in pure and applied science and a major component of high—technology industrial applications, for example, for magnetic recording and information storage and retrieval. This book presents relevant theoretical techniques and summarizes the optical, electronic, and nuclear experimental techniques used in studying the magnetic properties of such systems. Methods of sample preparation and characterization are also discussed. The book provides an up—to—date account of recent developments in this active interdisciplinary field.