A casino is a building or room in which gambling games are played. The games are operated by a person or persons authorized by law to do so. Casinos are usually located in cities with large populations or tourist destinations. The games offered in casinos include table games (such as blackjack and craps), slot machines, and other electronic devices such as video poker and keno. Some casinos also offer sports betting and horse racing.

In modern times, many casinos have been owned by real estate investors and hotel chains, who have the deep pockets needed to run them without fear of mob interference. The casinos are often built with fountains, towers or replicas of famous landmarks. The casinos make money by charging players a percentage of their bets for the privilege of playing there. This amount is known as the house edge or vigorish.

Casinos make a larger proportion of their income from slot machines than from any other game. These machines are simple to use: the player inserts a coin or paper ticket with a barcode, then pulls a lever or pushes a button. The machine then displays bands of varying colored shapes on reels (either physical ones or a video representation). If the right pattern appears, the player wins a predetermined amount of money.

Security at a casino is typically divided between a physical security force and a specialized surveillance department. The physical security force patrols the casino and responds to calls for assistance or reports of suspicious or definite criminal activity. The surveillance department monitors the casino using closed circuit television and other electronic devices.