A casino is a gambling establishment that allows customers to gamble by playing games of chance or skill, and in some cases both. The most common games include poker, roulette, blackjack, and slot machines. Other casinos offer more specialized games, such as tournaments or video poker. Many casinos also have restaurants and bars. Some even have top-notch hotels and spas.

Despite their reputation as places of excess, modern casinos tend to be much more focused on customer service than on maximizing profit. They frequently give out perks to encourage more spending and reward loyalty, such as complimentary rooms or meals. In addition, they employ specialized security departments that oversee their closed circuit television systems, often known as the eye in the sky.

These systems are especially important in games where a high percentage of money is lost—such as the game of craps, where the house edge can be as high as 16%. In games with a slight element of skill, such as blackjack or video poker, the house edge is calculated using mathematically determined odds that ensure that the house will win more than a player on average, even with optimal strategy.

While the vast majority of casino patrons are recreational, some gamblers are professional or semi-professional. In 2005, a study conducted by Roper Reports GfK and TNS found that the average American casino gambler was a forty-six-year-old woman from a household with above-average income. Other studies have found that more than half of casino gamblers are female.