The casino (plural: casinos) is an establishment where people can gamble. Some casinos offer a wide variety of games, while others specialize in certain types of gambling, such as poker or craps. Most casinos earn their money by charging a percentage of each bet to the players, a practice known as vigorish or rake. Other sources of revenue include complimentary goods and services, such as drinks or hotel rooms, given to high-spending patrons; these are called comps. Some casinos also collect a percentage of the winnings from slot machines, which are usually paid out at a set percentage of the total bets made on them.
Although gambling probably predates written history, the modern casino as a place to find a variety of gambling activities under one roof did not appear until the 16th century. Earlier casinos were often private clubs for rich people, like the ridotti in Italy.
In the United States, legal casinos grew rapidly after World War II. The first were in Nevada, where the popularity of Las Vegas led to a proliferation of casinos that eventually spread across the state and nationwide. Casinos also grew in popularity on American Indian reservations and on riverboats.
Casinos employ a large number of people to keep their gambling operations running smoothly. Security personnel patrol the gaming floors and monitor closed circuit television for signs of suspicious or blatant cheating. Table managers and pit bosses watch over the tables with a more sweeping view of the games, keeping an eye out for patterns that could indicate cheating.