A casino (also called a gambling hall or casin) is a place where people gamble. It is also a popular destination for tourists and locals looking for entertainment. The first casinos were founded in the 19th century, and their popularity has since grown immensely. Today, casinos can be found all over the world, with some of the most famous being located in Monte Carlo, France; Estoril, Portugal; Corfu, Greece; and Baden-Baden and Bad Homburg von der Höhe, Germany.

In the United States, legal casino gambling began in Atlantic City in 1978 and later spread to other American cities and to various Indian reservations, which are exempt from state antigambling laws. Most casinos are operated by specialized gaming companies and regulated by a central authority. Modern casinos use a combination of physical security forces and specialized surveillance departments. Casinos must know their house edges and variances to optimize their profits, so they hire mathematicians and computer programmers who specialize in gaming analysis.

Some casino games have a skill element, and players who possess sufficient skills to eliminate the inherent long-term house edge are known as advantage players. The skill element can be found in card games like blackjack and poker, in which the player competes against the dealer, as well as in table games like roulette and craps, in which the player competes against other players.

Due to the large amount of currency handled within a casino, both patrons and staff may be tempted to cheat or steal, either in collusion or independently. In order to prevent this, most casinos employ security measures such as closed circuit television and a strong police presence.