Addiction is a compulsion to repeat a behavior regardless of its consequences. A person who is addicted is sometimes called an addict. Many drugs or behaviors can precipitate a pattern of conditions recognized as addiction, which include a craving for more of the drug or behavior, increased physiological tolerance to exposure, and withdrawal symptoms in the absence of the stimulus. Most drugs and behaviors that directly provide either pleasure or relief from pain pose a risk of dependency. Addictions can also be formed due to opponent process reactions. For example the terror of jumping out of an airplane is rewarded with intense pleasure when the parachute opens. Because of opponent process criminal behavior, running, stealing, violence, acting, test taking can become habit forming.