A casino is a place where a variety of gambling activities are available. Although gambling likely existed for millennia, the idea of a central venue that offered multiple types of games sprung up in the 16th century during a flurry of popularity. It was not unusual for wealthy Italian aristocrats to hold private parties, called ridotti, in which the primary activity was gambling on various games of chance, even though the practice was technically illegal.

Modern casinos offer many amenities in addition to gambling, ranging from free drinks and stage shows to restaurants and shopping. They may also be equipped with elaborate surveillance systems, including a bank of monitors that provide a high-tech eye-in-the-sky view of the entire casino floor. Despite these luxuries, gambling accounts for only a small portion of the total revenue generated by casinos. Something about the ambiance of the casino — possibly its overwhelming presence of money — seems to encourage cheating and stealing, either in collusion or at random. Therefore, casinos devote a great deal of time, effort and expense to security.

Most casino money is made from slot machines, which are based on randomness rather than player skill. A player inserts a coin or paper ticket and pushes a button. Then varying bands of colored shapes roll on reels (actual physical or video). If the right combination is struck, the machine pays out a predetermined amount. Slot machines are the primary source of income for most American casinos, which usually demand a 1 percent advantage or less.