A casino or gambling house is an establishment that allows patrons to gamble by playing games of chance, and in some cases with an element of skill. Customers play for money or goods, and some casinos host live entertainment events such as stand-up comedy shows and concerts. Casinos are often built near or combined with hotels, resorts, restaurants, retail shops, and cruise ships. Some states have laws regulating the licensing and operation of casinos.

Originally, the term meant simply a public hall for music and dancing, but by the second half of the 19th century, it had come to refer to a collection of gaming or gambling rooms. The classic example is the Casino de Monte-Carlo, which opened in 1863 and became a major source of income for the principality of Monaco. Modern casinos are typically large, luxurious facilities with high ceilings and elaborate decor, designed to impress the paying customer. They may feature several hundred or even thousands of slot machines and gambling tables, along with one or more bars and restaurants.

Patrons are encouraged to gamble, and casinos have security measures in place to prevent cheating or stealing. In addition to a physical security force, many have specialized departments that monitor closed circuit television for suspicious or definite criminal activity.