This book is written for anybody who is curious about nature and motion. Have you ever asked: Why do people, animals, things, images and space move? The answer leads to many adventures; this volume presents those due to the discovery that there is a smallest change value in nature. This smallest change value, the quantumof action, leads towhat is called quantum physics. In the structure of modern physics, shown in Figure 1, quantum physics covers three points; this volume covers the introduction to the point in the lower right: the foundations of quantum theory. The present introduction to quantum physics.