Substance abuse refers to the harmful or hazardous use of psychoactive substances, including illicit drugs, prescription drugs, and alcohol. It is a pattern of substance use that can lead to a range of negative consequences, including health problems, legal issues, and social problems. Substance abuse involves using drugs or alcohol in ways that are harmful to the individual or others around them, such as driving while under the influence or engaging in risky behaviors. Substance abuse can lead to addiction or substance use disorder, which is a chronic, relapsing condition characterized by a pattern of drug or alcohol use that causes significant impairment or distress.