This book examines rare earth elements (REEs), materials, and metals that are critical to modern life. These serve as crucial ingredients in the latest technologies including electronics, electric motors, magnets, batteries, generators, energy storage systems (supercapacitors/pseudocapacitors), specialty alloys, and other emerging applications. REEs are used in various sectors including health care, transportation, power generation, petroleum refining, and consumer electronics. The Science of Rare Earth Elements: Concepts and Applications defines these elements, their histories, properties, and current and potential future applications across a wide range of industries across the world. It also discusses the environmental benefits, such as components in electric vehicles, wind turbines, solar applications, and energy storage systems. Conversely, the book also examines the liabilities of mining these REEs.