No country that wants to live in this atomic age can stand idly by in the face of the sweeping advances taking place every hour in the field of atomic energy. Those who fail to advance will inevitably fall behind, and others will overtake them and grow stronger. The path to this is clear in the chapters of this book, which begins with a definition of energy, its various types and sources, then explains nuclear reactors, in which energy is generated from uranium and other atomic elements. It then goes on to explain the radioactivity of natural materials, as well as the radioactivity acquired by materials artificially due to radiation, and the numerous applications of radioactive isotopes in industry, agriculture, medicine, and scientific research in various fields. The author concludes with a comprehensive overview of the new horizons that atomic energy has revealed and opened up to science.