A casino is a facility where people can play gambling games, such as poker and blackjack. Casinos also offer entertainment like shows and sporting events. They are usually operated by large companies. Casinos are located in cities or on Indian reservations. Some states have laws against them, but many do not. Casinos often compete with each other, and they use many different techniques to lure gamblers and keep them playing. They may use scents or flashy decorations, and they sometimes offer perks to frequent customers.

A survey of American casino patrons conducted by Gemini Research in 2002 found that the most popular game was slot machines. A majority of respondents also chose card games, including blackjack and poker. Other popular games included bingo and keno, but table games and gambling on sports/racing events each received less than 10% of the vote. Most respondents reported that they went to casinos to have fun and socialize with friends and family.

Casinos must make money in order to stay in business, so the mathematical odds are always against game players. As a result, it is rare for a single game to produce a profit for any player, even over a long period of time. To offset this, casinos offer a wide range of incentives to keep people gambling, such as free drinks and cigarettes while gambling, reduced-fare transportation and luxury living quarters.

In the United States, casinos were first established in Atlantic City in 1978, and then began appearing on American Indian reservations during the 1980s, where they are not subject to state antigambling statutes. By the early twenty-first century, they were found in all fifty states and numerous other countries.