This book provides an overview of the origins and evolution of the periodic system from its prehistory to the latest synthetic elements and possible future additions. The periodic system of the elements first emerged as a comprehensive classificatory and predictive tool for chemistry during the 1860s. Its subsequent embodiment in various versions has made it one of the most recognizable icons of science. Based primarily on a symposium titled “150 Years of the Periodic Table” and held at the August 2019 national meeting of the American Chemical Society, this book describes the origins of the periodic law, developments that led to its acceptance, chemical families that the system struggled to accommodate, extension of the periodic system to include synthetic elements, and various cultural aspects of the system that were celebrated during the International Year of the Periodic Table.