This document discusses drugs and drug addiction. It defines drugs as substances that change a person's mental or physical state. Drugs can be legal or illegal and are categorized as depressants, hallucinogens, or stimulants based on how they affect the central nervous system. The document then discusses drug addiction as a complex brain disease and treatments that use behavioral therapies and medication. It explores reasons why people use drugs and how drugs are made from plants, processed plant products, or synthetic chemicals. Finally, it outlines common methods of taking drugs such as swallowing, breathing, snorting, injecting, or through the skin.