A casino is a building or large room used for gambling. The term may also refer to a company that operates a casino. As of February 2009, there are more than 1,000 casinos in the United States. Most are located in Nevada and are owned by private individuals, corporations, or Native American tribes. The most successful ones rake in billions of dollars each year, benefiting their owners, employees, and local governments.
Many casino games are based on chance, although some have an element of skill. Most have mathematically determined odds that give the house an advantage over the players, a factor known as the house edge. In poker, the house takes a small percentage of each wager, a fee called the rake. In table games like roulette and craps, the casino employs special systems to monitor the accuracy of the wheel and dice and alert personnel quickly to any anomaly.
According to a survey by Gemini Research in March 2002, the most popular casino gambling game is slot machines, followed by poker and blackjack. In a second-place tie were bingo and keno. Other games, such as baccarat and sports/racing betting, are less popular.
Because of the large amounts of money involved, security is a major concern for both patrons and staff at casino establishments. The majority of casinos use cameras and other technological means to monitor the facility. Some casinos have catwalks above the gaming floor, allowing surveillance personnel to look down on players through one-way glass.