A casino (also known as a gambling house or a gaming room) is an establishment for certain types of gambling. Casinos are most often built near or combined with hotels, restaurants, retail shopping, cruise ships, and other tourist attractions. They may also feature entertainment venues such as theatres and nightclubs. In the United States, there are over 1,000 casinos. The Las Vegas Valley has the highest concentration of casinos, followed by Atlantic City and Chicago.

Casinos have long been a popular source of entertainment for many people. The origins of gambling are obscure, but it is believed that some form of it has been practiced throughout history in nearly every society. Despite being forbidden in some countries, casinos continue to thrive around the world and offer an exciting way to pass time or make money.

Most casinos offer a variety of games, from roulette and blackjack to video poker and baccarat. Table games such as craps and baccarat are the most popular. In the United States, the majority of casino revenue comes from slot machines and (from the 1980s) video poker. These generate large amounts of cash through high-volume, rapid play at sums ranging from five cents to a dollar or more.

Casinos must be secure, and their patrons need to feel safe and be able to trust that the game results are fair. To that end, most casinos employ security measures including cameras and trained personnel. Some casinos use more elaborate systems such as an “eye-in-the-sky” that can watch each table, window, and doorway at the same time.