A casino is an establishment for gambling. Casinos are most often built near or combined with hotels, restaurants, retail shops, and tourist attractions. In the United States, casinos are licensed and regulated by state gaming control boards. Casinos are also found on American Indian reservations and in some other countries.

Most casino games provide a predictable long-term advantage to the house, known as the house edge or vigorish, with the exception of skill-based games such as blackjack and video poker, where players can reduce the house edge by using proper strategy. Casinos make their profits from the house edge and vigorish, as well as from the comparatively large sums betted on certain games such as roulette and craps. Some casinos also generate income from the use of coin-operated machines, such as slot machines and video poker.

Modern casinos employ extensive security measures to prevent cheating and stealing by both patrons and employees. These measures include a physical security force and a specialized surveillance department. Many casinos have catwalks over the casino floor that allow surveillance personnel to look directly down on the tables and slots through one-way glass.

Gambling is legal in most US states, but there are two states where all forms of gambling are illegal: Alaska and Utah. Casinos are regulated by state gaming control boards and industry organizations. A person must be at least 21 years old to gamble in most regulated casinos, though the age limit varies by state and type of gambling.