Reflecting contemporary knowledge, this is a much-needed and comprehensive overview of the field. Topical reviews written by foremost scientists explain the trends and latest advances in a clear and detailed way, focusing on the correlations between electronic structure and magnetic properties. By maintaining a balance between theory and experiment, the book provides a guide for both advanced students and specialists to this research area. It will help them evaluate their own experimental observations and serve as a basis for the design of new magnetic materials. A unique reference work, indispensable for everyone concerned with the phenomena of magnetism.