Casino (also known as a gaming hall) is an entertainment complex that offers gambling and some other events. The casino industry generates billions of dollars each year in profits for the corporations, investors, and Native American tribes that own and operate casinos. Gambling is the main activity at casinos, which are also a major source of revenue for state and local governments. Casinos offer a wide variety of games that include slot machines, blackjack, roulette, craps, keno, and poker. In the United States, there are over 4,000 casinos, including massive resorts and small card rooms in bars and restaurants. Casinos are also present at many racetracks as racinos and in some cities with legalized gaming, such as Atlantic City, New Jersey, and Reno, Nevada.

In the United States, casinos are largely privately owned by individuals or corporations. The majority are located in Las Vegas and other large cities, with some operating on cruise ships, at Indian reservations, and in airports. Casinos are usually regulated by federal and state laws, with some jurisdictions having additional regulations for specific types of casinos or activities.

Casinos attract gamblers with glitzy attractions that stimulate the senses and induce a feeling of excitement and mystery. Bright lights, dazzling colors, and even the clang of coins dropping help to create the desired atmosphere. Red is a popular color in casino decoration because it is thought to increase gambling energy and make patrons lose track of time.