A casino or gambling house is a type of establishment where people can gamble. The exact origin of gambling is unknown, but it is believed to date back to ancient Mesopotamia and Rome. Modern casinos have a wide variety of games for gamblers to choose from. Some of these include gaming machines, table games, and random number games. Some casinos also offer live entertainment, such as concerts or comedy shows.

In the United States, casinos are generally licensed and regulated by state governments. Many of the larger ones are located in Las Vegas, though there are casinos elsewhere in the country. Several American Indian reservations have casinos, which are exempt from state antigambling laws. Casinos are often combined with hotels or resorts and may be located in tourist destinations.

The primary source of income for casinos is the monetary winnings of players. This money is typically won by playing poker, blackjack, and other table games. In these games, the players compete against the house rather than against each other, and the house edge is determined by the rules of the game. The house edge can be reduced by skillful play, such as card counting.

Other casino revenue comes from slot machines and video poker, which pay out a percentage of the total amount wagered. These games require less skill than other casino games and can be played by any number of players, though they usually have high house edges and variable variance. Because of their economic importance, these games are the focus of much research by gaming mathematicians.