A casino is an establishment for gambling. It is often combined with a hotel, restaurant, retail shopping, or cruise ship. Casinos are also known as gaming houses or gambling halls.

In the United States, casinos were once run by organized crime syndicates, but since federal crackdowns and the threat of losing their license at any hint of mob involvement, they have generally been operated by reputable businesses such as real estate investors and hotel chains. Despite the positive economic effects, critics contend that casinos shift spending away from other forms of local entertainment; that compulsive gambling has devastating social and psychological impacts on families; and that the money spent treating problem gamblers essentially negates any financial benefits that casinos might bring to a community.

Casinos use a variety of tricks to attract gamblers. They are arranged in a maze-like fashion so that wandering patrons are continually enticed by new gambling options. The clinking of slot machines and the shuffling of cards create constant background noise. The lighting is bright and exciting; more than 15,000 miles (24,100 km) of neon tubing illuminate the casinos along the Las Vegas Strip.

Casinos make their money by accepting bets on a wide range of events that depend on chance, including the outcome of a game of poker or blackjack and the drawing of a winning lottery ticket. Some games, such as roulette and craps, have an inherent long-term advantage for the casino, while others, such as baccarat and blackjack, allow players to use skills that reduce the house edge to less than one percent.