A casino is a facility where gambling activities take place. Casinos can range in size from tiny card rooms to massive resorts and are located in cities, towns, islands, and countries around the world. They make billions of dollars each year for the private companies, investors, and Native American tribes that own them and for the state and local governments that permit them to operate.

In the past, casinos were run by organized crime groups, but mob control has faded as real estate developers and hotel chains have purchased them and consolidated their operations. Large casinos are generally upscale facilities that offer a variety of entertainment and recreational activities in addition to gambling. They may feature restaurants, bars, shops, and even spas and museums. Some are opulent glass-and-steel temples to overindulgence; others are more low-key and traditional.

Most casinos provide patrons with free or reduced-fare transportation, meals, and living quarters in addition to the opportunity to gamble. Casinos also have surveillance systems that monitor activities both within and outside their walls. They use catwalks to allow security personnel to look down, often through one-way mirrors, on patrons at games such as blackjack, roulette, and baccarat. They also use video cameras in their poker rooms to supervise players and collect rakes (commissions on bets).

Gambling is a popular pastime in many countries, although it is illegal in some jurisdictions. Casinos, which offer games of chance and sometimes skill, attract millions of visitors each year and generate enormous profits for their owners.