A casino is a building or room where certain types of gambling take place. Casinos can be built on land or water, and they often include gambling tables for card games and dice, as well as slot machines. Many casinos also have restaurants, bars, hotels and non-gambling game rooms. They earn billions of dollars in profits each year from gamblers who risk their money in hopes of winning big.
Although gambling probably predates recorded history (with primitive protodice and carved six-sided dice found in archaeological sites), the modern casino as a venue for all kinds of gambling did not appear until the 16th century, when a gaming craze swept Europe. A casino is usually a large building with a wide variety of ways to gamble and has many security measures.
Security starts with the staff on the floor, who watch patrons play their favorite games and make sure everything goes as it should. Dealers are heavily trained and can easily spot blatant cheating like palming or marking cards, and table managers and pit bosses have a broader view to spot suspicious betting patterns. Elaborate surveillance systems offer a high-tech eye-in-the-sky to monitor every table, window and doorway in the entire casino at once.
In addition to their variety of games, most casinos make a significant portion of their income from slot machines, which are the easiest for players to understand. A player puts in money and pulls a handle or pushes a button, and bands of colored shapes roll on reels (actual physical ones or video representations). If the right pattern appears, the player wins a predetermined amount of money.