A casino is a building or room in which gambling games are played. It may also contain food and beverage services and stage shows. Casinos are usually heavily guarded, and patrons must present valid identification and are subject to random searches. In addition, gambling is generally only legal in jurisdictions where it is regulated by state law.
Gambling was illegal throughout much of the United States until 1931, when Nevada became the first state to legalize it. Until then, organized crime groups dominated the business, but federal crackdowns and the risk of losing a gambling license at even the faintest hint of mob involvement kept legitimate businessmen from getting involved in casinos.
To attract gamblers, casinos use a variety of tricks. They rely on bright lights and the sound of bells, whistles, and clanging coins to stimulate the senses of sight and hearing. They often display gaudy decorations in the color red, which is thought to make people lose track of time. Clocks are rarely used in casinos, and windows are often obscured.
Casino security is complicated, because both patrons and staff may be tempted to cheat or steal. However, the routines and patterns of casino games tend to generate recognizable reactions and actions, so it is easier for security personnel to spot suspicious behavior. Moreover, technology is being increasingly employed to oversee the actual games themselves. For instance, in chip tracking, betting chips with built-in microcircuitry interact with electronic systems to enable casinos to monitor precisely how much is wagered minute by minute, and to discover quickly any statistical deviation from expected results.