Final answer:
Addiction refers to compulsive drug use despite negative consequences. Dependence can be physical and/or psychological. Tolerance is when more of the drug is needed for the same effects.
Step-by-step explanation:
Addiction refers to the compulsive use of a drug despite the negative consequences that such use may entail. Dependence may be physical and/or psychological. Physical dependence involves changes in normal bodily functions, and a person experiences withdrawal symptoms when they stop using the drug. Tolerance is linked to physiological dependence, and it occurs when a person requires more and more of the drug to achieve effects previously experienced at lower doses.