Casino is a gaming establishment offering a wide variety of gambling games. Historically, these facilities have been located in cities known for their entertainment offerings such as Las Vegas and Atlantic City. In recent years, casinos have also appeared on American Indian reservations, which are exempt from state antigambling laws and attract visitors from many parts of the world.

Although some casino games have a skill element, most are pure chance. As such, the house always has an advantage over the players. This advantage, mathematically determined through game rules and optimal play (without counting cards), is called the house edge. The house also earns money from other sources such as a commission on slot machines and a percentage of the pot in games like poker that involve players competing against each other.

Gambling has been popular throughout history. Its precise origin is unknown, but it is believed to have existed in nearly every culture around the globe at one time or another. Today, casinos are an important part of the entertainment industry and are found in virtually every country worldwide.

The largest concentration of casinos is in the United States, with more than 40 states now permitting some form of gambling. Nevada is the leading gambling destination, followed by Atlantic City, New Jersey and Chicago. Most US casinos are very large, with a multitude of gambling rooms and other amenities such as restaurants, hotels, bars, non-gambling game areas and pools. A number of these casinos offer comps to their high-volume patrons, such as free hotel rooms, meals and tickets to shows.