A casino is a building or large room in which gambling is permitted. It has a variety of games of chance for players to gamble upon. Casinos are also known as gaming establishments and can be found in the United States, Europe, and elsewhere around the world. In the United States, casinos are generally licensed and regulated by state governments. Most of the larger casinos are in Las Vegas, and it is estimated that almost 40 percent of all gambling revenues in the state come from there.

Most casinos offer a wide variety of gambling games, including poker, blackjack, and slot machines. Some games involve some degree of player skill, but all casinos have built-in advantages that make the house the winner over time. These advantages are known as the house edge and variance. While skilled players can decrease the house edge with careful play, the reality is that the casino will always make money over the long run.

In the 21st century, casinos have become increasingly sophisticated in their use of technology. Many now use video surveillance to monitor patrons and employees, and the latest technology is used to oversee the actual games themselves. For example, in “chip tracking,” betting chips with built-in microcircuitry interact with electronic systems in the table to enable casinos to oversee exactly how much is wagered minute-by-minute and to be warned quickly of any anomaly; and roulette wheels are electronically monitored regularly to discover any statistical deviations from expected results.