A Casino is a building or room where people can play gambling games. Casinos also serve alcohol and food and are usually open 24 hours a day. Casinos are most often located in resorts, hotels, or tourist attractions. They can also be found in other places such as racetracks and on Native American reservations. Most casinos are owned by large companies that often franchise them.

The casino industry has grown rapidly since the late 1970s, when Atlantic City became the first state to permit commercial casino gambling. Since then, 28 states have legalized some form of casino gambling. Many of the largest casinos are in Las Vegas, Nevada; others are in Reno and Atlantic City. In addition to the traditional casino games such as blackjack and poker, most casinos offer sports betting.

Most casino games have a house edge, which is the long-term advantage of the casino. Some have skill elements, and players with sufficient skills can eliminate the house edge or reduce its effect. Casinos hire mathematicians to analyze game rules and develop strategies that minimize the house advantage. This work is known as gaming analysis.

Humans are attracted to bright lights, so more than 15,000 miles of neon tubing decorate the casino buildings along the Las Vegas Strip. Casinos also use audio and visual stimuli to encourage gamblers to stay longer. Large casinos spend millions of dollars determining what colors, sounds, and scents appeal to the most gamblers.