A casino is a gambling establishment where patrons gamble by playing games of chance or in some cases, skill. The term is also used for facilities for mass entertainment and recreation, such as a nightclub or theater. Casinos may also offer table games such as blackjack, roulette, and poker, or video machines like slots and video poker. In games where patrons play against each other, casinos often make a profit by taking a percentage of the pot or charging an hourly fee to use the tables.

Unlike lottery games or Internet gambling, casino gambling is social in nature. In addition to being surrounded by others while gambling, players are frequently shouted at by fellow patrons or encouraged by waiters serving drinks from mobile bars. The lights, noise, and excitement of a casino are designed to attract attention and stimulate gambling.

In the United States, casino gambling first became popular after Nevada legalized it in 1931. Later, Atlantic City, New Jersey, and American Indian reservations opened their own casinos. Casinos have also spread to other countries, such as the Philippines and South America.

The casino industry has become increasingly competitive in the United States, with many locations competing for the same clientele. Some are so exclusive that only high rollers, who place large bets, are invited. These clients are rewarded with free hotel rooms, meals, tickets to shows or even limousine service and airline tickets. These perks, called comps, are intended to offset the fact that five percent of casino patrons are addicted and therefore generate only 25 percent of profits.