A casino is a place where people play games of chance for money. Often the word is used to describe the elaborate facilities that house gambling activities, but there have been less-lush places that have housed similar activities and still been called casinos. Casinos are characterized by their loud noise and bright lights, and they usually have some form of entertainment such as music or stage shows. Some casinos are regulated by government agencies, while others are not. The gambling industry is a major source of employment and income for many countries.

Despite the excitement and flashy lights, most people who gamble in casinos do so out of economic necessity rather than out of pure pleasure. According to a 2005 study by Roper Reports GfK NOP and the U.S. Gaming Panel, the average casino gambler is a forty-six-year-old woman from a household with an above-average income. The casino industry is very competitive, and even large-scale operations such as those in Las Vegas compete with each other for the same high-income customers.

The casino industry is also characterized by its need for security. Casinos have a built-in advantage in all their games, and the math behind that advantage makes it very rare for a patron to win more than the casino expects to make from his or her bets. Casinos spend a lot of time and effort on security, from surveillance cameras that provide a high-tech eye-in-the-sky to sophisticated systems that monitor individual bets minute by minute and alert security personnel to any statistical deviations from expected results.