When most people think of casinos, they picture one of the megaresorts in Las Vegas—a dazzling place filled with neon lights, fun and games. But a casino is much broader than that. Merriam-Webster defines it as “a building or room used for social amusements, specifically gambling.”

Casinos are essentially places where people can try their luck at games of chance, such as roulette and slot machines, or games that involve cards or dice. They can also include table games like poker and blackjack, where players play against the house or other patrons instead of against the machine.

In addition to creating stimulating atmospheres, casinos focus on customer service. They reward frequent visitors with free items and discounts, known as comps. They also offer special rooms for high rollers, whose bets can run into the tens of thousands of dollars.

The early history of casinos is often linked to organized crime. Gangsters had plenty of money from drug dealing, extortion and other illegal rackets, and they wanted to invest it. Initially, they provided the bankroll for Reno and Las Vegas casinos. In time they became more involved, taking sole or partial ownership of some.

In the twentieth century, casinos began to spread across the world as governments relaxed their antigambling laws. They also opened on American Indian reservations, which were exempt from state laws. And they became more sophisticated, using cameras and other technology to spot cheating. They also shifted their investment strategies, targeting the high-rollers who could generate substantial profits for them.