This work discusses quantum optics and investigates the quantum properties of interactions between atoms and laser fields. It is divided into three parts. Part I introduces the elementary theory of the interaction between atoms and light. Part II provides a concentrated discussion on the quantum properties of light fields. Part III deals with the quantum dynamic properties of the atoms interacting with laser fields. This book can be used as a text for both graduate and undergraduate students. It should also benefit scientists who are interested in quantum optics and theoretical physics.