A casino, also known as a gambling establishment or a gaming house, is a facility that offers various forms of legal gambling. Casinos are operated by governments, private corporations, or quasi-governmental organizations and are usually located in areas with high population density. They offer a wide variety of games, such as slot machines, table games (such as poker, blackjack, and roulette), and sometimes entertainment shows. To gamble in a casino, customers must be of legal age and must follow the rules and regulations of the establishment.

In the United States, casinos are most commonly found in Las Vegas and other locations in Nevada, where commercialized gambling has been permitted since 1931. In the 1980s, however, casinos began to appear on American Indian reservations, which are exempt from state antigambling laws. Currently, 40 states allow some form of casino gambling.

Some casinos specialize in specific types of games. For example, some feature Far Eastern games such as sic bo and fan-tan, while others offer traditional European games like baccarat, chemin de fer, and poker. Casinos often employ staff to oversee security and enforce the rules of play. They may use cameras and other technological measures, and they typically require players to keep their hands visible at all times when playing card games.

Casinos make money by charging a commission to players who win. To maximize their profits, casinos hire mathematicians and computer programmers to calculate the house edge and variance of each game.