A casino is a building where people can play games of chance and gamble. Casinos offer a variety of games, including blackjack, roulette, poker and slot machines. The games are regulated by state laws. Some states prohibit certain games, while others allow them in specified locations. The word casino is used worldwide, although it has different meanings in different languages. It may refer to a single casino, a group of casinos, or an entire city or country.

Gambling probably predates recorded history, with primitive protodice and carved six-sided dice found in archaeological sites. The modern casino as a central place to find many ways to gamble under one roof probably developed in the 16th century during a gambling craze in Europe. Italian aristocrats would gather in small clubs called ridotti (roughly, private rooms) to gamble and socialize. Because of their seamy image, most legitimate businessmen were reluctant to get involved with casinos until organized crime began funding them. Mafia money flowed steadily into Reno and Las Vegas, where the mobsters often took sole or partial ownership of some casinos and even influenced the outcomes of games by threatening casino personnel.

In America, casinos rely on slot machines and video poker machines for most of their income. Players put in money and press a button to spin the reels; if the right pattern comes up, they win a predetermined amount of money. The advantage over the player is typically less than two percent, but this amount varies from game to game.