A casino (also called a gaming house or a gambling establishment) is an establishment where people can gamble. Modern casinos are like indoor amusement parks for adults with the vast majority of the entertainment (and profits for the owners) coming from gambling. Slot machines, blackjack, roulette, craps and keno provide the billions in profits raked in by casinos every year.

While many of the games played at a casino involve an element of skill, most have mathematically determined odds that ensure the house will always win in the long run. These odds are known as the house edge. The casinos make money by taking a percentage of all bets placed (called the rake) or by charging fees for special services. Casinos also earn money by selling drinks, food and other merchandise.

In the United States, casinos are most often found in the states of Nevada and New Jersey. They can also be found on American Indian reservations and in some European countries. In the 1970s, casino gambling became legalized in Atlantic City, and in the 1980s, several other states changed their laws to allow casinos.

Casinos use a variety of technologies to monitor the games and protect their guests. For example, some casinos have special chips with built-in microcircuitry that can track the amount wagered minute by minute and alert staff if there is an unusual trend. Other casinos have video cameras positioned throughout the casino to observe activities at tables and slots. Casinos also have catwalks in the ceiling that enable security personnel to look directly down on activities at the tables and slots through one-way glass.