A casino is a public room where gambling games (such as roulette, baccarat, blackjack, poker, and slot machines) are played. Some casinos also host gaming tournaments and offer other forms of gambling such as lottery-type games. A casino is considered a gambling establishment under state law. In the United States, legalized casino gambling began in Nevada in 1931 and now accounts for nearly 40 percent of all tax revenue in that state. Other famous casino cities include Monte-Carlo, Estoril, and Baden-Baden in Germany.

Gambling is a popular pastime in many countries and has been an integral part of social culture throughout history. People visit casinos for the thrill of the game and to test their luck at winning a jackpot. In addition to gambling, casinos often serve food and beverages, provide entertainment through concerts and comedy shows, and offer a variety of other amenities such as hotel rooms and spas.

Modern casinos are designed with security in mind, with most having a dedicated casino security department that patrols the premises and responds to calls for assistance or suspicious activity. Some casinos have catwalks in the ceiling above the gaming floor that allow surveillance personnel to look directly down, through one-way glass, on the activities at the tables and slot machines. Some casinos employ specialized casino security guards to act as bodyguards for high-rollers and other VIP guests. They are generally trained to recognize and defuse conflict between patrons as well as to protect the assets of the casino.