Addictions can include, but are not limited to, alcohol abuse, drug abuse, exercise abuse, pornography and gambling. Classic hallmarks of addiction include: impaired control over substances/behavior, preoccupation with substance/behavior, continued use despite consequences, and denial. Habits and patterns associated with addiction are typically characterized by immediate gratification (short-term reward), coupled with delayed deleterious effects (long-term costs). Physiological dependence occurs when the body has to adjust to the substance by incorporating the substance into its 'normal' functioning. This state creates the conditions of tolerance andwithdrawal. Tolerance is the process by which the body continually adapts to the substance and requires increasingly larger amounts to achieve the original effects. Withdrawal refers to physical and psychological symptoms people experience when reducing or discontinuing a substance the body had become dependent on. Symptoms of withdrawal generally include but are not limited to anxiety, irritability, intense cravings for the substance, nausea, hallucinations, headaches, cold sweats, and tremors.