Final answer:
Drug addiction is a behavior causing a craving for a substance or activity, while withdrawal involves pain and distress when ceasing the substance use. Dependence can be physical or psychological, and tolerance refers to needing increased amounts of the drug for the same effect.
Step-by-step explanation:
A drug addiction is a compulsive behavior that leads people to physically or mentally crave a substance or activity. An automatic behavior is one that becomes automatic and occurs without needing conscious thought. When breaking a dependency, a person may go through withdrawal, which can cause severe physical pain and psychological distress.
Addiction refers to the compulsive use of a drug despite the negative consequences that such use may entail. Physical dependence involves changes in normal bodily functions—the user will experience withdrawal from the drug upon cessation of use. In contrast, psychological dependence signifies an emotional need for the drug, often to relieve psychological distress. Tolerance is closely related to physiological dependence and occurs when a person requires more of the drug to achieve effects that were previously attained with lower doses.