A casino is an establishment for certain types of gambling. The term may also refer to a building that houses one or more such establishments. In modern usage, it almost always refers to a large facility that offers a wide variety of games of chance and skill, and is particularly noted for its elegance, service, and entertainment value. Casinos may also serve as social centers for people to meet in comfortable surroundings. The majority of casinos in the United States are located in Las Vegas, Nevada; Atlantic City, New Jersey; and Chicago, Illinois. Many other cities have smaller casinos.

Casinos earn money by accepting bets from patrons on various games of chance or skill, and in some cases by charging admission. The amount of money a casino expects to earn from each game is determined by mathematical odds that guarantee the house a profit, which it shares with players through an advantage known as the “house edge.” This percentage can be small (less than two percent) or large (up to several hundred percent) depending on the game and how it is played.

Due to the high volume of money handled within a casino, both patrons and staff may be tempted to cheat or steal, either in collusion with others or independently; for this reason most casinos have security measures in place. These can include visible security cameras, random auditing of gaming tables, and a system of “chip tracking” that electronically monitors betting chips minute-by-minute to quickly discover any statistical deviation from expected results.