A casino (or gaming house) is a facility for certain types of gambling. Casinos are often combined with hotels, restaurants, retail shops, and other entertainment venues. They may also be located on cruise ships or in other tourist destinations. The industry is regulated by laws and regulations. In the United States, casinos are classified as financial institutions and must report large cash transactions to federal regulators.

Something about gambling seems to encourage people to cheat or steal, so casinos spend a lot of time and money on security. Many have elaborate surveillance systems with “eye-in-the-sky” cameras that watch every table, window, and doorway. Cameras can be adjusted to focus on suspicious patrons, and video feeds are stored so they can be reviewed after the fact. Casinos also employ a staff of roving detectives to monitor the floor and look for suspicious behavior.

Gambling has been a part of almost every culture throughout history. While the exact origins of gambling are unknown, it is generally believed to have begun in ancient Mesopotamia and spread from there throughout the world. Today, there are more than 3,000 legal casinos in operation worldwide. In the United States, most are located in Nevada, and some in New Jersey and Atlantic City. Casinos are also common on American Indian reservations, where state antigambling laws do not apply. In addition, there are numerous illegal pai gow and craps parlors throughout the country. In total, about 51 million Americans—roughly a quarter of all adults over the age of 21—visit casinos each year.