Casinos are places where people can play a wide variety of games of chance and skill for real money. They may be massive resorts with many different types of entertainment, or they might be small card rooms in a bar or even at a truck stop. Some states have legalized casinos on land and others have allowed them to operate on riverboats, racetracks, and other venues. Regardless of their size, all casinos must adhere to strict rules and regulations to ensure player safety.

While gambling likely predates recorded history (with primitive protodice, cut knuckle bones, and carved six-sided dice found in archeological sites), the casino as an establishment where people can find many ways to gamble under one roof did not develop until the 16th century when a gambling craze swept Europe. People were eager to bet on everything from horses to battles and jousting, and they wanted a central location where they could do so.

The casino industry generates billions of dollars each year for the companies, investors, and Native American tribes that own and operate them. State and local governments also reap substantial revenues from casino gaming. Successful casinos earn a significant percentage of their profits from slot machines, which are typically the most popular games. Players insert money and pull a handle or push a button; varying bands of colored shapes roll on reels (actual physical ones or a video representation of them) and stop in a predetermined pattern to award a payout amount. Slot machines do not require any skills or strategy to play.