When you step into a casino, the atmosphere is like an indoor amusement park for adults. Lighted fountains, musical shows and lavish hotels add to the experience, but casinos wouldn’t exist without games of chance like slot machines, poker, blackjack and baccarat. They make up the bulk of the billions in profits that casinos rake in each year.

A casino’s enticing environment and the games of chance draw in gamblers from around the world. Despite the fact that gambling predates recorded history — primitive protodice and carved six-sided dice have been found in ancient archaeological sites — casinos as we know them didn’t develop until the 16th century, when Italian aristocrats held private parties at venues called ridotti [Source: Schwartz].

Gambling was illegal throughout much of the country until Nevada legalized it in 1931. But even after that, it took years for other states to follow suit.

Casinos offer free goods and services to their “good” patrons. These perks, known as comps, vary from free hotel rooms to discounted meals and show tickets. Big spenders receive more elaborate inducements like limo service and airline tickets.

Security starts on the casino floor, where employees keep their eyes peeled for suspicious gamblers. They’re trained to spot blatant cheating, such as palming cards or marking and switching dice. Elaborate surveillance systems provide a high-tech eye-in-the-sky, with cameras watching every table, window and doorway. They can be adjusted to focus on certain patrons by workers in a separate room filled with banks of security monitors.