A casino is a gambling establishment where a variety of games of chance are played. The games include craps, roulette, blackjack, poker, video poker, and baccarat. Most casinos offer a house edge, which is a mathematically determined advantage that the casino has over the players. This can vary between games, but is generally lower than two percent. Casinos also give away complimentary items to gamblers, and charge commissions on slot machines (known as rake).

Modern casinos use sophisticated technology to verify player identities and monitor game play. For example, in table games like poker, betting chips have microcircuitry that interacts with electronic systems to record the exact amount wagered minute by minute; and a system called eye-in-the-sky monitors every movement in the entire casino floor to quickly discover any suspicious patrons.

In addition to technological surveillance, casinos rely on security personnel and rules of conduct to deter cheating. Many casinos have mandatory dress codes and prohibit the use of cell phones or other devices, and they have pit bosses who oversee game play. In some cases, casinos will ban players who display signs of addiction or have a history of gambling-related problems.

For most of American history, casino gambling was illegal. Nevada became the first state to legalize it, but it took decades for other states to follow suit. During the 1980s, however, large hotel and real estate developers realized the potential profits of casinos. Today, there are more than 3,000 casinos nationwide, including floating casinos on barges and riverboats, and those in horse racetracks and at airports (known as racinos). The majority are located in Nevada, but other states have permitted casinos on Native American reservations and on the outskirts of major cities.