This book starts with a theoretical introduction of the rare earth materials, and it subsequently analyzes the essential characteristics of these materials from elements, compounds to physical chemistry and metal materials, etc. Under the supplementary explanation of experimental data and results, the research is gradually guided into the multi-domain application scene. Through extensive analyses, this book displays comprehensively the distinguished values of the rare earth materials and the theoretical, empirical, and practical significance of rare earth materials is unraveled. It also covers an exhaustive review of 17 rare earth elements, their characteristics, and more possibilities in physical chemistry, functional materials, metallurgy, composites and engineering, and their prospects in production and technical applications. In-depth account of the whole spectrum of rare earth material research makes this book a unique reference to academic researchers, students, and engineers.