When it comes to casinos, you probably think of the bright lights and big money of Las Vegas or Atlantic City. But there are casinos across the United States, from elegant spa towns that once hosted royalty and aristocracy to tiny mountain towns whose 19th century Wild West buildings now house slot machines and poker tables.

Casinos house gambling activities and are licensed to do so by the government. They offer many luxuries to attract gamblers, such as restaurants, free drinks, stage shows and dramatic scenery. But in order to be called a casino, the main purpose has to be gambling.

Most casinos are staffed with employees who watch over games and patrons. On the floor, dealers are heavily focused on their own game and can easily spot blatant cheating like palming or marking cards. Pit bosses and table managers have a broader view of the casino, looking for patterns in betting that may signal cheating. Elaborate surveillance systems have an eye-in-the-sky view of every room, table, window and doorway.

Casinos are considered financial institutions in the US, meaning they accept cash, exchange currency, issue checks and handle wire transfers. As such, they have to report to the federal government whenever a transaction amounts to more than $10,000 in a day. In addition, they have to keep track of all the chips that customers buy, redeem or lose. They also have to estimate how many chips may never be redeemed, since some will likely get lost or be taken as souvenirs.