A public room or building where gambling games (such as roulette, baccarat, blackjack, poker, and slot machines) are the principal activity. A casino may also host other entertainment activities such as shows and fine dining.

In the United States, casinos are typically located in cities with large populations and are often owned and operated by large gaming companies. Casinos are regulated by state and local governments. In addition, they must adhere to certain standards such as having adequate security and having a high payout percentage. Despite these regulations, casino employees and patrons can still be tempted to cheat or steal, especially when large sums of money are involved. To counter this, most casinos have various security measures such as cameras and security guards.

The legal age to gamble at a casino varies by state and type of game; in general, the minimum age is 21. Casinos also offer a variety of other betting products such as horse racing and pari-mutuel wagering. The most profitable games for casinos are those that have a low house edge and a high payout percentage. To calculate these odds, casino mathematicians use mathematical algorithms and computer programs.

In the United States, there are over 300 commercial casino operations. Most are located in Las Vegas, Nevada, but the industry has also expanded to Native American reservations and other locations that do not violate state laws on gambling. There are also a number of online casinos that allow players from the United States to place bets without traveling to a physical establishment.