A casino is a place where people can gamble and play games of chance. In some cases it may involve a small amount of skill, but in all instances the results of any gambling game are purely dependent on random chance. The precise origin of the word is unknown, but gambling in one form or another has almost certainly existed throughout history, from primitive protodice and carved knucklebones to modern lottery-style games. While the modern casino adds luxuries such as restaurants, free drinks and stage shows to its gambling activities, there have always been less extravagant places that would still qualify as casinos.

The most important characteristic of a casino is its security. Casinos spend a great deal of time and money on surveillance equipment. They also have a variety of rules that encourage patrons to behave appropriately and not cheat or steal. Despite these efforts, there is always some danger that a casino will lose money.

To protect their profits, casinos employ a variety of mathematically determined advantages, which they refer to as the house edge. In addition, they make sure that all bets are placed within an established range so that it is extremely unlikely for a patron to win more than the casino can afford to pay out.

Many casino games have predictable patterns that security personnel are trained to recognize, such as how dealers shuffle cards or the way in which players bet. Windows and clocks are also absent from casino floors, so patrons cannot easily be distracted by their surroundings.