Heroin is an illegal opioid drug derived from morphine, which is extracted from the opium poppy plant. It is typically found in a white or brown powder or as a black sticky substance known as "black tar heroin." Users often inject, snort, or smoke heroin to experience its intense euphoric effects, which can lead to rapid addiction. The drug works by binding to opioid receptors in the brain, resulting in pain relief and feelings of pleasure. However, heroin use can lead to severe health risks, including overdose, infectious diseases, and long-term changes in brain function. Treatment for addiction often involves medications like methadone or buprenorphine and counseling.