This document summarizes information about substance abuse and dependence. It discusses the health and social problems caused by commonly abused substances like alcohol, tobacco, cannabis, cocaine, amphetamines, inhalants, sedatives, hallucinogens, and opioids. Risk factors for substance abuse are discussed, including prenatal exposure, insecure attachment during infancy, aggression during childhood, lack of structure in school, and exposure to substance-using peers. Symptoms of acute intoxication, regular use, dependent use, and injecting drugs are outlined. Specific health issues related to smoking, alcohol, cannabis, cocaine, and other substances are also summarized.