Gambling is an activity in which something of value is risked on the outcome of an event primarily determined by chance. It has been part of human societies since prerecorded history, and is incorporated into many cultures through traditions, customs, and rites of passage.

Gambling has many negative impacts, including economic costs and personal social costs. In the United States, gambling is legal in most jurisdictions and takes many forms: pari-mutuels (horse and dog tracks, off-track betting parlors, jai alai), lotteries, casinos (slot machines, table games, etc.), racetracks, sports books and bookmaking (sports and horse racing). It can also occur in online poker rooms and other websites offering the ability to place bets on a variety of events.

When you gamble, your brain releases dopamine, a neurotransmitter that triggers excitement and the desire to win. This makes it difficult to recognize when you have had enough. People who have lower incomes are more susceptible to developing a problem, as are young people and men, according to research.

People who gamble often become secretive about their behavior, hiding gambling activities from friends and family members and lying to them when asked. They might be secretive because they think others will not understand their behavior or because they are trying to conceal their addiction from loved ones who may try to help them. They might also lie about how much they are spending on gambling, increasing bets in a desperate attempt to make up for lost money.