This book introduces the research process and principles of the controlled super-coupling nuclear fusion experiment at the Experimental Advanced Superconducting Tokamak (EAST) nuclear fusion reactor in Hefei, China. It uses straightforward language to explain how nuclear fusion can provide safe, environmentally friendly, clean, and inexhaustible energy in future. EAST is the world first fully superconducting, non-circular cross-section tokamak nuclear fusion experimental device, independently developed by the Chinese Academy of Sciences. This book helps demonstrate China cutting-edge scientific and technological advances to the rest of the world, helps spread the scientific spirit to people around the globe, and promotes prosperity and development. The book is intended for all non-experts who would like to learn more about nuclear energy and related technologies.