More than 51 million people—that’s more than a quarter of Americans over 21—visited casinos last year. From the glitz and glamour of Las Vegas to the teeming illegal pai gow parlors of New York, casino entertainment draws people from around the world.

Casinos are a major source of revenue for many states, and they also employ millions of workers, both directly and indirectly. Many of them are in tourist-heavy areas, such as Las Vegas, and some—like the Casino de Monte-Carlo in Monaco—are famous for their beauty or history.

Because large amounts of money are handled in a casino, there is always the temptation for patrons and staff to cheat or steal, either in collusion or individually. To discourage such behavior, casinos often use surveillance cameras throughout their facilities, and many have small black domes on the ceiling that are actually hidden microphones. Casinos are also known for their bright and sometimes gaudy floor and wall coverings; red is one of the most popular colors, as it has been shown to stimulate gambling activity.

Almost all casinos offer slot machines and table games. In addition, some have bingo halls and sports betting sections. Some even have restaurants. Many have live entertainment, such as comedians and concerts. Casinos also provide hotel rooms and other amenities. For high rollers, they might even offer private jets.