This book presents a comprehensive explanation of the main ideas and principles of atomic and nuclear physics and quantum mechanics.The author invites readers to plunge into the physics of micro-objects and to take a fascinating tour of the world of atoms and nuclei. The main questions under consideration are the structure of atoms, atomic nuclei, the substance and systematics of elementary particles, the processes of the creation of atomic nuclei and the evolution of stars as well as different applied aspects of the physics of micro-objects.