When most people think of a casino, they envision one of the megaresorts that define Las Vegas—a flashy hotel and entertainment complex blazing with neon lights and fun games. But the term casino, as defined by Merriam-Webster, is actually broader than that. A casino is any establishment for gambling.

Whether it’s a table game like blackjack conducted by live croupiers or a video poker machine, each casino game has a built-in advantage for the house. This advantage can be small—less than two percent—but it adds up over the millions of bets placed each year. The money earned from this advantage is the foundation for the casinos’ lavish appearances, including fountains, pyramids and towers and replicas of famous landmarks.

Because of the large amounts of currency handled, casinos are prone to theft by both patrons and staff. As a result, many casinos have elaborate security measures. Among them are surveillance cameras that monitor tables, change windows and doorways. In addition, some casinos employ “chip tracking,” in which betting chips have microcircuitry that interacts with electronic systems to oversee the exact amount of money wagered minute by minute and warn when there is a statistical deviation.

Mob money also flowed into Reno and Las Vegas during this period, but mafia figures were not content to merely finance the operations; they became personally involved, took sole or partial ownership of some casinos, and sought to influence the outcome of individual games. Federal crackdowns and the threat of losing a gaming license at even the faintest hint of mob involvement eventually drove these gangsters from their casinos.