A casino, or gaming house, is an establishment for certain types of gambling. Some casinos are built near or combined with hotels, restaurants, shopping, cruise ships, and other tourist attractions. Many casinos have a dress code and offer complimentary drinks and snacks to gamblers. The games played in the casino are based on chance, and in some cases skill. The house always has a mathematical advantage over the players, and this is called the house edge. Casinos also take a percentage of all wagers, known as the rake.

In the United States, casinos are licensed and regulated by state governments. They may operate on land or on water (such as riverboats) and are usually staffed with professional dealers. Some casinos are owned by local or regional Indian tribes. Some casinos specialize in specific games, such as craps, roulette, baccarat, and blackjack. Others provide entertainment by featuring live performers. In the twentieth century, casinos developed into complex facilities with sophisticated surveillance systems and security personnel.

In the early 1950s, organized crime provided a steady supply of money to casinos in Las Vegas and Reno. The mobster money helped legitimize the business, which had been tainted by its seamy image and was illegal in most other places. The mobsters became personally involved, taking sole or partial ownership of some casinos and influencing the outcomes of some games with their cash. Technology has also improved casino security and gaming. Chips with built-in microcircuitry allow the casino to monitor them minute by minute, and electronic surveillance allows operators to immediately detect any anomalies in game results.