A casino is a facility where people gamble by playing games of chance or skill. Some casinos are massive resorts, while others are small card rooms. Regardless of size, successful casinos bring in billions of dollars each year for investors, corporations, and Native American tribes. In addition, gambling generates a significant amount of tax revenue for local governments.

While most casino patrons don’t win big, they do spend a lot of money. As a result, security is a high priority. Casinos use surveillance systems to keep track of the action and spot cheating. In addition, employees are trained to look for suspicious betting patterns.

Most casino games are based on probability and require some degree of luck, although some, like poker, allow for strategic play. In general, the house always wins, and this advantage is mathematically determined. The percentage of expected value that the house will make is called the house edge.

When casinos first appeared in the United States, many were funded by organized crime figures. Mobster money flowed steadily into Reno and Las Vegas, giving the industry a tainted image. As a result, legitimate businessmen were reluctant to invest in casinos. Mafia gangsters, however, had plenty of cash from illegal drug dealing, extortion and other rackets, so they took over sole or partial ownership of many casinos and controlled their operation through bribery and intimidation. This era of “mob casinos” lasted until the late 1950s. Then, legitimate businesses began to take over in the form of casinos run by skilled operators.