This document defines and describes different types of drugs: stimulants which increase alertness, depressants which reduce arousal, narcotics/opioids which relieve pain, hallucinogens which alter awareness, and inhalants which are inhaled. It notes that drug abuse means unwarranted drug use, addiction means continued use for non-food purposes, and dependence means a physiological need to consume a substance. Common reasons for substance abuse are to relax, for excitement, to fit in socially, for enjoyment, out of curiosity, or to avoid pain.