A casino is a building or large room used for gambling. Its walls may be lined with slot machines, or they may have table games such as blackjack and roulette. A casino can also contain other entertainment venues such as bars and restaurants. In some countries, casinos are licensed and regulated by government authorities. Casinos are often combined with hotels and resorts, and they are often built on or near rivers, lakes, mountains, or other attractions.

The precise origin of gambling is unknown, with the first documented evidence dating back to 2300 BC in China. Dice and playing cards appeared later in Ancient Rome and, by the 16th century, were commonplace in European cities. However, the concept of a casino as a place for people to gamble in one location did not appear until much later.

Modern casinos make use of a wide range of security measures. These include the use of cameras to monitor patrons and their behavior, and the use of a random number generator (RNG) to assure that all bets are placed randomly. Security personnel are trained to spot a variety of potential cheating techniques, including palming, marking, and switching cards or dice. They also watch for betting patterns that could indicate collusion.

Casinos rely on their customers for the vast majority of their revenue, so they try to encourage big bettors with elaborate inducements. These can include free spectacular entertainment, luxury hotel rooms and transportation, and reduced-fare food and drink. Casinos also make money by charging a commission on winning bets or by taking a percentage of the pot of money. Some studies suggest that the economic benefits of casinos are offset by the costs associated with problem gambling.