Casino (plural casinos) is a facility for certain types of gambling. It is also known as a gaming house or, in military usage, as a caón or cassino (Spanish for officers’ mess). It is sometimes combined with hotels, resorts, restaurants, retail shops, and cruise ships. Casinos may be located in city centers, vacation areas, or on cruise ships. They often feature multiple floors with a variety of games, including roulette, blackjack, and poker. Many have outdoor patios and are surrounded by water features or mountains.

Casino is a popular form of entertainment in the United States, and it is legal in 40 states. The Las Vegas metropolitan area is home to the largest concentration of casinos, followed by Atlantic City and Chicago. Casinos are also popular in other parts of the world, especially in countries where gambling is legal or where tourist infrastructure is well developed.

The precise origin of gambling is unknown, but it is widely believed that it has existed in some form since ancient times. There is evidence of gambling activity in Mesopotamia, Greece, Rome and Elizabethan England, and it was common among the ancient Aztecs and Incas. Today, gambling is a huge industry that affects communities and economies around the world. It is estimated that around 51 million people visit casinos in the United States every year. These figures do not include those who travel to other countries to gamble, or those who play in illegal pai gow parlors and other underground operations.