The rare earth elements are a group of nearly indistinguishable and lustrous silvery-white soft heavy metals. They react slowly with cold water to form hydroxides and ignite at high temperatures. These elements are used in the production of highly efficient magnets, glasses, alloys and electronics. They are also used in the manufacture of fuel cells, mobile phones, computers, optical fiber cables, hybrid cells, and LEDs. In the agricultural sector, rare earth elements are used to increase the growth of the plants, increase crop yield, and improve stress resistance in plants. Some of the rare earth elements are scandium, yttrium, cerium, promethium, europium, dysprosium and ytterbium. This book provides significant information to help develop a good understanding of the rare earth elements. A number of latest researches have been included to keep the readers up-to-date with the global concepts in this area of study. The book aims to serve as a resource guide for students and experts alike and contribute to the growth of research on these elements.