A casino is a gambling establishment offering an array of games of chance or, in some cases, skill. Many casinos also offer a wide variety of food and beverage options. They can be found in cities and towns around the world, and are usually operated by large hotel chains or local companies. Some states and countries regulate the operations of casinos. Others do not. Casinos in the United States are mainly located in Atlantic City, New Jersey; Las Vegas; and Chicago. In addition, some American Indian reservations have legalized casinos.

Most casino games provide a mathematical expectation of winning for the house, called the house edge. This advantage is typically a small percentage of total bets and may be reduced by skilled play or by using statistical deviations (such as card counting). Casinos earn additional income by taking a commission on certain games, called rakes.

Despite their large size, casino operations are often closely monitored by security personnel and police. Various measures are used to prevent cheating or theft by patrons and staff, including video surveillance systems, metal detectors, and one-way mirrors. Some casinos also employ catwalks in the ceiling that allow security personnel to look down, through one-way glass, on activities on the casino floor below.

In a few cities, such as Monte Carlo, the city is almost defined by its casino. However, in most cases, a casino is an integral part of a larger resort or entertainment complex.