A casino, or gaming house, is an establishment for certain types of gambling. Modern casinos often offer a variety of games and are found near or combined with hotels, restaurants, retail shops, cruise ships, and other tourist attractions. Many states have legalized casino gambling.

In a casino, gamblers bet on games of chance, and the house makes money by taking a percentage of total winnings or charging an hourly fee to players. While casino luxuries such as stage shows, shopping centers, and elaborate themes help draw in crowds, the billions in profits raked in by casinos are largely due to games of chance like slots, blackjack, roulette, craps, and keno.

Gambling has been a popular pastime throughout much of human history, and many ancient societies built social structures around it. Modern casinos make extensive use of technology to ensure the fairness of games, and some have strict rules about player conduct.

As the casino industry evolved, organized crime figures provided large amounts of capital to expand and operate new casinos. Mob money brought a veneer of respectability to Reno and Las Vegas, but it also brought corruption and intimidation. Legitimate businessmen were unwilling to become involved in the tainted gambling businesses, even though they offered high returns.

Despite the glamour of casino games and the millions in profits they generate, casinos are inherently risky. Patrons and employees may cheat, steal, or bribe in collusion, and casino security must be alert to these threats. A modern casino typically has a physical security force and a specialized surveillance department, both of which work closely together to deter criminal activity.