Modern casinos are like indoor amusement parks for adults, with dazzling lights, jumbotrons and a mindblowing variety of games. But they wouldn’t exist without gamblers, who provide the billions of dollars in profits that allow casino owners to build huge hotels, fountains, replicas of famous landmarks and awe-inspiring gaming rooms.

Casino originally referred to a public room for music and dancing in the 1740s, but by 1792 it was used to describe a building designed for card games and gambling. The word was borrowed from Italian, where it was used to refer to a “little house”—perhaps a shed or a cabin.

Most casinos make their money by charging players to play games of chance (or skill, such as baccarat or blackjack). Each game has a built-in statistical advantage for the house that amounts to a percentage of all bets placed. This is sometimes called the “house edge” or “vig,” and it helps ensure that casinos won’t lose money over time.

In the 1950s, organized crime figures realized the potential of the new gambling business and began funneling money into Reno and Las Vegas. Mob money gave casinos a certain je ne sais quoi, but federal crackdowns and the fear of losing a gaming license at the slightest hint of Mafia involvement meant that legitimate businesses bought out the mobsters and took over. Today, casino ownership is usually in the hands of wealthy real estate investors and hotel chains. The casinos themselves often have a maze of nongambling activities, such as top-notch restaurants and spas.