A casino (also known as a gambling hall) is a building or room used for social amusements, especially gambling. In the United States, a casino is a place where people can gamble legally. It also is a place where people can socialize and watch sports. Some casinos are large and extravagant; others are small, with fewer amenities. People may gamble by playing games of chance or skill, such as craps, poker, roulette, baccarat, and blackjack. Some casinos offer only one type of game, while others have many different kinds.

Gambling has been a part of human culture for millennia. Archeologists have found dice in China dating to 2300 BC, and card games appeared in Europe during the 1400s. Today, the casino is a global industry with millions of patrons and billions in revenue. Casinos bring in profits not only for the corporations and investors that own them, but also for state and local governments and Native American tribes. The success of a casino depends on its location, because it must attract tourists to offset operating expenses.

Most Americans think of a casino as an exotic locale, such as Venice or Monaco, but casinos are located in many other places, from small towns to major cities. In America, the largest casino is in Las Vegas, followed by Atlantic City and Chicago. Regardless of their size, most casinos use technology to enhance security and monitor play. For example, in some casinos, betting chips have microcircuitry to enable them to be monitored minute by minute and to warn the casino immediately of any anomaly; roulette wheels are electronically supervised to detect statistical deviations from expected results quickly.