A casino is a gambling establishment, where patrons place wagers against the house or the dealer. Casino games are governed by strict rules, and winnings are calculated according to mathematical probabilities. In addition to slot machines, many casinos feature other popular games, such as poker and blackjack. Some are themed, with Ancient Rome, space and the movies being common themes.
Something about gambling (perhaps the large amounts of money involved) seems to encourage cheating and stealing, whether in collusion with casino staff or independently; that is why casinos spend so much time, effort and money on security. Besides the obvious, such as cameras and a heightened police presence, casino security also relies on simple tricks to catch cheaters. For instance, the way players react to the cards being dealt and the location of betting spots on the tables follow certain patterns that are easy for security personnel to spot.
In the early days of American casinos, organized crime figures supplied the money for some of them. They also took sole or partial ownership of some casinos and exerted considerable influence over decisions by managers and workers. But federal crackdowns on mobsters and the threat of losing a gaming license at even the slightest hint of mob involvement allowed legitimate businessmen to take over most of the casinos, which today operate under tightly controlled rules.
Casinos make their money by offering perks to their best customers, known as comps. These include free hotel rooms, meals, show tickets and other gifts to those who play long enough and bet big money. Most casinos have clubs similar to airline frequent flyer programs, with cards that are swiped before each game to tally points.