A casino (or gambling house) is an establishment where gambling activities take place. It can be located in a land-based setting such as Nevada, New Jersey, and New York or on cruise ships, military bases, and Indian reservations. It can also be found in many other places including hotel towers, retail shopping centers, and even theme parks.

In the United States, casinos are primarily legalized in Nevada, New Jersey, and Atlantic City. Several other states have legalized casinos on American Indian reservations. In the 1980s, casino gaming began to spread outside these areas as state laws were relaxed. Today, there are over 340 casinos in Nevada alone.

Something about the casino environment encourages patrons to cheat and steal, either in collusion with each other or independently. Consequently, casinos employ a large number of security measures to deter these activities. In addition to cameras and other technological devices, security personnel constantly watch patrons. They note betting patterns that may indicate cheating and other irregularities, and monitor tables for signs of suspicious activity.

Casinos make money by charging a commission on bets placed by players. This is known as the vig or rake, and it gives the casino a mathematical advantage over each player. In addition to this edge, casinos often offer free entertainment and other inducements to attract high bettors. These rewards include free spectacular shows, luxury accommodations, and reduced-fare transportation. In the past, smaller incentives were offered to lesser bettors as well.