In the past few years our understanding of magnetic behavior, once thought to be mature, has enjoyed a new impetus from contributions ranging from molecular chemistry, materials chemistry and sciences to solid-state physics. The book spans recent trends in magnetism for molecule - as well as inorganic-based materials, with emphasis on new phenomena being explored from both experimental and theoretical points of view with the aim of understanding magnetism at the atomic scale. 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.