This book focuses on the similarities and distinctions between substance and non-substance addictions, offering a detailed discussion of their mechanisms, diagnosis, and treatment. It addresses selected prospects that will shape future studies on addiction. Addiction is a global problem that costs millions of lives tremendous damage year after year. These two primary types of addictions share certain common mechanisms, which involve a dysfunction of the neural reward system and specific gene transcription factors. While they also have key differences. The information is covered in this book systematically and provides readers with a better understanding of drug and behavioral addictions. This book is valuable for researchers, students and anyone who are interested in additions research. In this 2nd edition, all chapters have been updated, and new chapters are added. The new chapter covers research in recent years, on the role of neurotransmitters including dopamine, serotonin, opioid, glutamate and norepinephrine in substance addiction and non-substance addiction, in order to provide a fuller discussion on the similarities and differences in their neurobiological mechanisms.