A casino is a place where people can gamble and play games of chance. While musical shows, lighted fountains and shopping centers provide much of the ambiance, casinos are most famous for gambling and, more specifically, the billions in profits that they rake in annually from slot machines, blackjack, roulette, craps and other games. Even your grandmother might have taken weekend bus trips to the local casino with her friends to pursue her luck there.

A modern casino might look like an indoor amusement park for adults, complete with a variety of games and a large buffet. But behind the glitz, there is an essential truth: The vast majority of casino profits come from games that require a minimum amount of skill to play.

The game choices in a casino are almost endless, but the most popular include blackjack, video poker and slots. Casinos can vary in the rules they apply to each of these, but they all require some degree of skill and knowledge.

Modern casinos rely on sophisticated technology to oversee their patrons and the games themselves. For example, “chip tracking” enables casinos to monitor exactly what bets are placed minute-by-minute and to warn players of any discrepancies; roulette wheels are electronically monitored to discover statistical deviations quickly.

In some cases, casinos might reward good customers with comps, free rooms, meals or show tickets. In other cases, they might use surveillance cameras to watch what’s going on in the casino. These sophisticated systems, known as “eyes in the sky,” can be a boon for security personnel and help to deter criminal activity.