Whether they are giant resorts or small card rooms, casinos generate billions of dollars each year for the companies, investors, Native American tribes, and state governments that operate them. They also draw millions of tourists to towns and cities across the globe. In the United States alone, 51 million people—or nearly one quarter of all adults over 21—visited a casino in 2002.

A casino is a facility for gambling and games of chance that involves betting against the house—or the “house edge.” The house advantage can be very small (lower than two percent) but it adds up over time, allowing casinos to build fountains, pyramids, towers, and replicas of famous landmarks. The house edge also provides the money that pays for dealers, table managers, and pit bosses to keep their eyes on patrons in case of cheating.

In addition to baccarat, poker, blackjack, and roulette tables, a casino might feature an array of video poker machines or a selection of slot games. Unlike table games, slot machines are based on random numbers generated by computers and cannot be controlled or tampered with. A casino’s security staff monitors the slot machines through banks of cameras that can be adjusted to focus on specific suspicious patrons.

Casinos are designed to encourage gamblers to spend more money than they intended by offering a variety of perks, including free food and drinks, travel packages, hotel stays, show tickets, and other amenities. These perks are known as comps, and they are key to the profitability of casinos.