In this book, the fundamentals of magnetism are treated, starting at an introductory level. The origin of magnetic moments, the response to an applied magnetic field, and the various interactions giving rise to different types of magnetic ordering in solids are presented and many examples are given. Crystalline-electric-field effects are treated at a level that is sufficient to provide the basic knowledge necessary in understanding the properties of materials in which these effects play a role. Itinerant-electron magnetism is presented on a similar basis. Particular attention has been given to magnetocrystalline magnetic anisotropy and the magnetocaloric effect. Also, the usual techniques for magnetic measurements are presented. About half of the book is devoted to magnetic materials and the properties that make them suitable for numerous applications. The state of the art is presented of permanent magnets, high-density recording materials, soft-magnetic materials, Invar alloys and magnetostrictive materials. Many references are given.Table of contents: 1. Introduction. 2. The origin of atomic moments. 3. Paramagnetism of free ions. 4. The magnetically ordered state. 5. Crystal fields. 6. Diamagnetism. 7. Itinerant-electron magnetism. 8. Some basic concepts and units. 9. Measurement techniques. 10. Caloric effects. 11. Magnetic anisotropy. 12. Permanent magnets. 13. High-density recording media. 14. Soft-magnetic materials. 15. Invar alloys. 16. Magnetostrictive materials. Author index. Subject index.