Over the years there have been a number of excellent textbooks on the subject of magnetism. Among these we must include Bozorth's Ferromagnetism (1950), Chikazumi's Physics of Magnetism (1964) and Cullity's Introduction to Magnetic Materials (1972). However at present there is no up to date general textbook on magnetism. This book will, I hope, satisfy this need. It is a book for the newcomer to magnetism, and so I anticipate it will be useful as a text for final-year undergraduate courses in magnetism and magnetic materials or for graduate courses. I would also hope that it will be useful to the researcher who, for one reason or another, is beginning a study of magnetism and needs an introductory general text. In this case the extensive references to the literature of magnetism given in the text should prove useful in enabling the reader to gain rapid access to the most important papers on the subject. For the expert there are of course already numerous excellent specialist works, of which the most significant is Wohlfarth's four-volume series Ferromagnetic Materials. The book was conceived as a whole and deals with the fundamentals of magnetism in Chapters 1 to 11, and the principal applications in Chapters 12 to 16.