A casino is an establishment that allows its patrons to gamble by playing games of chance. These games generally involve a significant element of risk, and the house always has a mathematical advantage over players. The amount of this advantage is usually determined by the rules of the game, and it may be quantified using a formula known as expected value. Casinos often earn money by charging a commission, called the rake, to players who play certain games against each other. In some games, such as poker, the rake is taken by a casino employee who deals the cards.

Modern casinos offer a wide variety of entertainment options, including restaurants, bars, and shows. They may also feature hotel rooms, retail shops, and other amenities. Some are owned by governments and operate under their jurisdictions, while others are private enterprises. Most of them are located in cities with large populations, but a few are in rural areas.

Gambling in some form is practiced throughout the world, and it is legal in most countries. Casinos are an important source of income for many states, and they are a major tourist attraction in some places. Most casinos have gaming machines, table games, and random number games. Most gaming machines are operated by computer programs, and the table games are run by casino employees. The random number games are based on the selection of numbers from a computerized random number generator. In the United States, the largest casinos are found in Las Vegas, Nevada. A few states have legalized gambling in other locations.