The definition of drug addiction is the the compulsive idea of drugs, no matter how harmful it is. Drugs mostly attack the brain of the user. It affects a circuit called the reward circuit. It is the circuit that tells a person what they need to keep doing to survive, like food and water. Using drugs more makes the circuit tell you to want it more which leads to addiction. Biology, environment, and development plays a big role in who becomes addicted or not.
