Addiction results when a person ingests a substance (alcohol, cocaine, or nicotine, for example) or repeatedly takes part in an activity (gambling) that can be pleasurable, but the continued use of which becomes compulsive and interferes with everyday life. Common addictions include: -- Alcohol abuse -- Drug abuse -- Exercise abuse -- Pornography -- Gambling Classic symptoms of addiction include impaired control over substances/behavior, preoccupation with substance/behavior, continued use despite consequences, and denial. Behavior patterns and habits associated with addiction are commonly characterized by the pursuit of immediate gratification, coupled with negative long-term effects. Physiological dependence results when the body is unable to function normally in the absence of the substance or behavior. This state produces the conditions of tolerance and withdrawl. Tolerance is the result of the body requiring larger volumes of the substance or stimulus in order to achieve the original effects. Withdrawal is the physical and psychological symptoms experienced when the body no longer receives the substance in the same quantities it has become reliant upon.