A casino, sometimes called a gaming hall or a gambling house, is a place where people play games of chance for money. Gambling has long been a popular form of entertainment in many societies throughout history, and casinos provide an atmosphere of noise, light and excitement where it is possible to win or lose large sums of money in short periods of time. Casinos earn profits by taking a portion of the total bet amount or charging an hourly fee for games such as poker.

To help gamblers make decisions about how much to wager, casino employees provide information on odds and probability. A good casino will also have a team of mathematicians and computer programmers who track the performance of individual table games and slot machines to optimize their profit margins. This work is often outsourced to professional gaming mathematicians and analysts.

The vast majority of casino patrons are not high rollers who spend thousands of dollars a hand, but ordinary folk who enjoy visiting their local casino for the social interaction and excitement of playing games of chance. According to the Washington, DC-based American Gaming Association, in 2002 more than 51 million people visited a casino in the United States alone. Including those who visit foreign casinos, the figure rises to nearly 100 million.

Casinos attract their customers by providing a variety of amenities and stimuli that encourage gambling, such as free drinks, food and stage shows. In addition, they may use bright and cheery floor and wall coverings that help to increase the energy level in the room and stimulate gambling activity. They also employ the color red, which is thought to make patrons lose track of time and concentrate more on their gambling.