A brain disorder manifested by compulsive substance use despite of its adverse consequences is known as addiction. The two main properties which attract addictive stimuli are that the substances are often reinforcing, and appear to be intrinsically rewarding. Some of the common types of addiction include drug addiction, gambling addiction, food addiction and sexual addiction. Any substance which on inhalation, consumption, injection and absorption causes a temporary physiological and psychological change, is called a drug. The process of medical treatment for treating one's dependency on psychoactive substances, like alcohol, street drugs and prescription drugs is known as drug rehabilitation. This book will provide interesting topics for research which interested readers can take up. It includes some of the vital pieces of work being conducted across the world, on various topics related to drug addiction. This book will prove to be immensely beneficial to students and researchers in this field.