A casino, also known as a gaming establishment or a gambling house, is a building or room in which people wager money on various events, usually with the outcome determined by chance. Casinos are most often associated with games of chance such as roulette, craps, and blackjack, but may also include games of skill such as poker and sports betting. Regardless of the games offered, casinos are businesses and must therefore generate a profit. To this end, they offer bettors free spectacular entertainment, reduced-fare transportation and hotel rooms, complimentary drinks and cigarettes while gambling, and other inducements. The mathematical odds are uniformly against game players, however, and even the most skilled and lucky players will lose money on average in the long run.

Many casinos use a variety of tricks to lure gamblers and keep them gambling as long as possible, such as arranging games in a mazelike fashion so that wandering patrons will be constantly enticed by more gambling options. They also employ sophisticated electronic systems to monitor their games and detect any deviation from expected results, such as in the case of crooked dice or a skewed roulette wheel.

The casino industry is regulated and legalized in most jurisdictions worldwide. In some cases, government-owned enterprises operate casinos, but most are private businesses. In the United States, a number of Indian reservations have also opened casinos. The first commercial casinos began appearing in Atlantic City during the late 1970s, and since then the industry has spread to many American states.