A casino is a room or building in which gambling games (such as roulette, blackjack, poker, and slot machines) are played. It also refers to the games themselves, and the organizations that operate them. In the United States, casinos are primarily located in Nevada and New Jersey. Many casinos are large resorts, with multiple restaurants, bars, and entertainment venues. Others are smaller, standalone buildings. Some casinos specialize in particular games, such as baccarat and craps. The term is also used for a group of gaming rooms in a larger facility, such as a hotel.

Most casino games have a predictable long-term advantage for the house, known as the house edge. Some have a skill element, and players who use sufficient skills can eliminate this advantage. These players are referred to as advantage players. Casinos earn money from these games by taking a commission from winnings, or a percentage of the total amount wagered, called the vigorish. In games where players compete against each other, such as poker, the casino makes its profit by taking a share of each pot or charging an hourly fee to play.

Although most states allow some form of casino gambling, not all do. Some are better known than others for their casinos, such as Las Vegas and Atlantic City. In addition to their gaming floors, these facilities often have high-end restaurants and spas. They may also feature golf courses, circus acts, and live entertainment.