Whether you want to hit the slots, spin the roulette wheel, lay down some chips at the craps table or put on your best poker face, casinos are the perfect place to get that gambling itch scratched. And fortunately, there are many casino options in the U.S., many of them just a short drive away.

The casino industry generates billions of dollars in profits every year, mostly through gambling. Although musical shows, lighted fountains and elaborate themes help attract customers, the games of chance are what bring in the big bucks. Slot machines, blackjack, roulette, baccarat and poker are just a few of the casino games that make up most of the business. But how do they work? And how do casinos stay safe from cheaters and thiefs?

Casinos must be able to spot any suspicious activities, whether they are the result of patrons working in collusion or individually. That’s why most casinos spend a lot of money on security. The first line of defense are the security cameras located throughout the casino. Then there are the employees, both floor and managerial, who constantly look for anything out of the ordinary. Casino security people know the idiosyncrasies of each game and can quickly spot any unusual behavior, including palming, marking or switching cards and dice.

There are also some less obvious security measures. For example, some casinos have catwalks that run above the casino floor, allowing security personnel to view activities below through one-way glass. This allows the staff to quickly spot anyone who is trying to steal or cheat.