A casino is an establishment where people can take part in gambling activities. It may also be combined with hotels, restaurants, retail shops or other tourist attractions. It is usually open 24 hours a day and offers various types of gambling. In the United States, most casinos are located in Las Vegas and Atlantic City. However, they are becoming more common in many other parts of the world.

Although gambling probably existed in primitive forms as early as prehistoric times, the modern casino did not develop until the 16th century when a gambling craze swept Europe. Italian aristocrats would gather in private clubs known as ridotti to gamble and socialize. Because these clubs were technically illegal, they were rarely bothered by the police.

In the 1950s, mobster money flowed into Reno and Las Vegas, helping to establish their reputation as gambling meccas. But the mobsters were not content to just provide the funds; they took sole or partial ownership of casinos and used their clout to influence game results. Federal crackdowns and the threat of losing a license at even the slightest hint of Mafia involvement eventually drove these men out of the business.

Today, legitimate investors with deep pockets have replaced the mobsters as the backers of the new generation of casinos. Donald Trump and the Hilton hotel chain are two prominent examples. Because so much money changes hands in a casino, cheating and theft by patrons or staff are a constant concern. Most modern casinos rely on high-tech surveillance systems to monitor everything from the money changing rooms to the slot machines, which are wired so that any statistical deviations are immediately detectable.