A casino (also known as a gambling house or a gaming establishment) is an institution for certain types of gambling. Casinos are often built near or combined with hotels, restaurants, retail shopping, cruise ships or other tourist attractions. They may also be specialized in particular types of games, such as poker, or offer a variety of gaming options. Some casinos focus on customer service and provide perks to “frequent players”, such as free room nights, meals or tickets to shows.

Casinos are generally considered to be establishments where it is legal to gamble, although that is not always the case. Gambling is usually based on chance, although some games have an element of skill. Casinos make money by charging patrons for the use of their facilities, most notably through the vigorish or rake taken from games such as poker and blackjack. Some casinos also earn revenue through a percentage of bets placed on slot machines and video poker machines.

For the first few decades of their existence, most casinos were owned by organized crime figures and had a shady reputation. Mob funds kept the casinos going but eventually the owners sought more stable and legitimate funding. Real estate developers and hotel chains with deep pockets bought out the mobsters and casinos now operate with the faint whiff of legality. Modern casinos rely heavily on technology to monitor their operations. For example, some slot machines have built in microcircuitry that tracks the amount of money wagered minute by minute and alerts the casino if any statistical deviation occurs; roulette wheels are electronically monitored for anomalies.