A casino is a building or room where various games of chance are played. Gambling is the primary activity in casinos, and the most popular games are slot machines, blackjack, roulette, baccarat, and craps. Other games, such as keno and pai gow, are sometimes played as well. In modern times, casinos are primarily resorts that feature entertainment and gambling in addition to other amenities for their guests. A famous example is the Bellagio, which is known for its fountain shows and luxurious accommodations. Casinos also exist in many cities, on American Indian reservations and on cruise ships.

In the United States, an estimated 51 million people — roughly a quarter of all adults over 21 — visited a casino in 2002. These visitors spend billions of dollars each year, and casinos have a variety of ways to attract these customers, including free food and drinks. Casinos are businesses, and they must balance the interests of their customers with those of the house, which wins more than it loses. They do this by setting mathematical expectancies for each game that they offer, which are calculated by mathematicians who specialize in casino games.

Casinos are also able to prevent cheating and theft by observing their patrons’ behavior and imposing rules on them. For example, a patron is not allowed to move their cards around the table and must keep their hands visible at all times while playing poker. They are also required to use chips instead of cash, which makes it harder for them to conceal a cheating strategy or hidden hand.