Casino is an entertainment venue where customers gamble by playing games of chance or, in the case of poker and some other card games, with a small element of skill. Most games have a built-in statistical advantage for the house, which earns the casino money over time from the millions of bets placed by its patrons. The house edge is usually much less than two percent, but this small profit adds up over time. Casinos often earn additional revenue from giving away complimentary items, known as comps, to players and taking a commission on winning bets, called the rake.

Gambling in some form predates recorded history, with primitive prototype dice and carved knuckle bones found in archaeological digs, but the idea of a place where people could find a variety of ways to gamble under one roof did not develop until the 16th century when Europeans began holding private gambling parties, or ridotti, in places like the elegant spa town of Baden-Baden. These gatherings became more popular as large public casinos were closed by the Inquisition.

Modern casinos are run by investors who have deep pockets and are able to withstand the risk of losing their investments. They also benefit from the huge amount of business they attract from tourists who visit to gamble. According to a 2005 survey by Roper Reports GfK NOP and the U.S. Gaming Panel by TNS, the average casino gambler is a forty-six-year-old woman from a household with above-average income. Casinos make more profit from high-rollers who spend a lot of money, so they are given special rooms and other perks to entice them to keep coming back.