Gambling is risking something of value on an outcome that is determined at least in part by chance in the hope of winning something else of value. It can include betting on horse races or other sports events, buying lottery or scratch-off tickets, playing card games, and even betting in office pools. Skill can improve the chances of winning some gambling activities but is not a necessary component. For example, a knowledge of card-playing strategies may increase the probability of winning in some poker games, or a knowledge of horses and jockeys might improve predictions about probable outcomes in horse races.
The meaning and significance of gambling varies widely across cultures, societies, and historical periods. People who gamble frequently, or whose behavior causes them distress or personal problems, are often referred to as problem gamblers. They can be described as having a variety of different disorders, depending on the definitions and criteria used for diagnosis.
The causes of pathological gambling are not well understood. It has been suggested that the disorder is caused by a combination of biological, psychological, social, and environmental factors. There are several models that have been proposed to explain the condition, including behavioral-environmental reasons, a general theory of addictions, and reward deficiency syndrome. Each of these models has some empirical support. However, there are also differences in perspective between researchers, psychiatrists, and other treatment care clinicians about what causes the disorder. This may contribute to disagreement about how the disorder should be classified and treated.