Gambling is an activity in which a person stakes or risks something of value upon the outcome of a future contingent event not under his or her control or influence, such as a game of chance, a race, or a lottery. It does not include bona fide business transactions such as the purchase or sale of securities and commodities, contracts of indemnity or guaranty, or life, health, and accident insurance.

Historically, gambling was considered immoral and largely illegal. Today, it is a popular recreational activity that takes many forms. It can be a private, social activity such as playing card games or dice with friends in a home setting, a commercial venture like casinos, or public events such as horse races and lottery drawings. It can also involve a variety of activities that combine risk and skill, such as shooting basketballs into a net. Gambling can also be used as a form of escapism or to meet the basic human need for thrills and status. Casinos are designed around this principle, promoting a sense of specialness and belonging.

There are several methodological challenges when examining the impacts of gambling. Attempts to quantify nonmonetary harms by assigning a monetary value can create bias. Research may also be confounded by the fact that gambling has both negative and positive impacts at the individual, interpersonal, and community/society levels. Some of these impacts are long-term and can change the life course of a gambler or even pass between generations.