Gambling is the betting of something of value on an uncertain event where there is a risk that one will lose it. The stakes could be money, or other items of value such as collectible games pieces (such as marbles, pogs and Magic: The Gathering). It may be conducted for a variety of reasons, including as a way to self-soothe unpleasant emotions, unwind, socialize or even to get rich.

Research shows that gambling can have serious, negative effects on individuals and society. The harms are not only financial, but can also have psychological, social, occupational and family consequences. A significant number of people experience problems with gambling to a degree that interferes with their daily life, causes distress or anxiety, and affects their relationships. In addition, some people develop a compulsive urge to gamble and are unable to control their spending or stop gambling despite the negative consequences.

A large portion of the population participates in some form of gambling, ranging from state-run lotteries to casino gambling and even the betting of small amounts of money on sports events by poorer people. However, gambling is not considered to be a socially desirable activity and has been associated with morally questionable behaviour, such as money laundering and criminal activities.

There is a great deal of debate about whether or not gambling should be classified as an addiction, and how it should be defined and measured. There are many factors that influence the behaviour of a person who is prone to problem gambling, which include genetics and personality, as well as cultural influences such as the social perception of gambling as an acceptable pastime.