An addiction is a state in which the body depends on a substance or an activity for normal functioning and may occur along with physical dependence, as in drug addiction. When the activity, drug or substance on which someone is dependent is suddenly removed, it will cause withdrawal, a characteristic set of signs and symptoms. Addiction is generally associated with increased drug tolerance.

Most people are social gamblers, who gamble for entertainment and typically don’t risk more than they can afford. If they should “chase” their losses to get even, they do so briefly. There is none of the preoccupation, long -term chasing, or progression of the pathological (compulsive) gambler. In referring to gambling, the terms “pathological” and “compulsive” are often used interchangeably. Compulsive is the layman’s term and the one used by Gamblers Anonymous. Pathological is preferred by clinicians and was introduced in 1980 when the American Psychiatric Association first recognized pathological gambling as a bona fide mental disorder and included it in its Diagnostic and Statistical Manual (DSM-lll). Compulsive gambling was thought a misnomer since, in the language of psychiatry, compulsive behavior is involuntary and “ego-dystonic” (external or foreign to the self). Examples of a compulsion would include repetitive hand washing or the irresistible urge to shout an obscenity. Pathological gambling, at least in its early stages, is typically experienced as pleasurable. Pathological gambling has been defined as a progressive disorder characterized by a continuous or periodic loss of control over gambling; a preoccupation with gambling and with obtaining money with which to gamble; irrational thinking; and a continuation of the behavior despite adverse consequences.
Substance abuse has come to refer to the overindulgence in and dependence of a drug or other chemical leading to effects that are detrimental to the individual's physical and mental health, or the welfare of others. The disorder is characterized by a pattern of continued pathological use of a medication, non-medically indicated drug or toxin, that results in repeated adverse social consequences related to drug use, such as failure to meet work, family, or school obligations, interpersonal conflicts, or legal problems. There are on-going debates as to the exact distinctions between substance abuse and substance dependence, but current practice standard distinguishes between the two by defining substance dependence in terms of physiological and behavioral symptoms of substance use, and substance abuse in terms of the social consequences of substance use. Substance abuse may lead to addiction or substance dependence. Medically, physiologic dependence requires the development of tolerance leading to withdrawal symptoms. Both abuse and dependence are distinct from addiction which involves a compulsion to continue using the substance despite the negative consequences, and may or may not involve chemical dependency. Dependence almost always implies abuse, but abuse frequently occurs without dependence, particularly when an individual first begins to abuse a substance. Dependence involves physiological processes while substance abuse reflects a complex interaction between the individual, the abused substance and society.