A casino (also known as a gambling house or a gaming hall) is an establishment for gambling. Modern casinos are highly regulated and offer a variety of games, including roulette, blackjack, poker, and sports betting. Casinos are located in a wide range of places, from seaside resorts to mountaintops. Some are owned by governmental or tribal organizations, while others are operated by private corporations. The most famous casino is in Monte Carlo, a city-state within the principality of Monaco.

Casinos are most often built near or combined with hotels, restaurants, retail shops, and tourist attractions. In addition to slot machines and table games, some casinos also feature top-billed entertainment shows such as high-flying circus acts and popular musician concerts.

The precise origin of gambling is unknown, but it is generally believed to have evolved from ancient rituals and ceremonies. In the 19th century, with the rise of railways and steamships, gambling became widely available to the masses. Its popularity has remained steady since then, and there are now casinos throughout the world.

The house edge is a mathematical advantage that the casino has over its patrons, and it ensures that the house will make a profit from all bets placed within an established limit. This advantage can be calculated using basic math and by referring to published tables of optimal play for various games, which are prepared by trained professional gaming mathematicians. In table games such as poker, the casino makes its money via a commission, called the rake.