Slot machine

A slot machine, fruit machine (British English), puggie (Scots), poker machine or pokie (Australian English and New Zealand English) is a gambling machine that creates a game of chance for its customers.

A slot machine's standard layout features a screen displaying three or more reels that "spin" when the game is activated. Some modern slot machines still include a lever as a skeuomorphic design trait to trigger play. However, the mechanical operations of early machines have been superseded by random number generators, and most are now operated using buttons and touchscreens.

Slot machines include one or more currency detectors that validate the form of payment, whether coin, banknote, voucher, or token. The machine pays out according to the pattern of symbols displayed when the reels stop "spinning". Slot machines are the most popular gambling method in casinos and contribute about 70% of the average U.S. casino's income.

Digital technology has resulted in variations in the original slot machine concept. As the player is essentially playing a video game, manufacturers can offer more interactive elements, such as advanced bonus rounds and more varied video graphics. Slot machines’ terminology, characteristics, and regulation vary by country of manufacture and use.

The "slot machine" term derives from the slots on the machine for inserting and retrieving coins. "Fruit machine" comes from the traditional fruit images on the spinning reels such as lemons and cherries. Slot machines are also known pejoratively as "one-armed bandits", alluding to the large mechanical levers affixed to the sides of early mechanical machines, and to the games' ability to empty players' pockets and wallets as thieves would.

Sittman and Pitt of Brooklyn, New York, developed a gambling machine in 1891 that was a precursor to the modern slot machine. It contained five drums holding a total of 50 card faces and was based on poker. The machine proved extremely popular, and soon many bars in the city had one or more of them. Players would insert a nickel and pull a lever, which would spin the drums and the cards that they held, the player hoping for a good poker hand. There was no direct payout mechanism, so a pair of kings might get the player a free beer, whereas a royal flush could pay out cigars or drinks; the prizes were wholly dependent upon what the establishment would offer. To improve the odds for the house, two cards were typically removed from the deck, the ten of spades and the jack of hearts, doubling the odds against winning a royal flush. The drums could also be rearranged to further reduce a player's chance of winning.

Because of the vast number of possible wins in the original poker-based game, it proved practically impossible to make a machine capable of awarding an automatic payout for all possible winning combinations. At some time between 1887 and 1895, Charles Fey of San Francisco, California, devised a much simpler automatic mechanism with three spinning reels containing a total of five symbols: horseshoes, diamonds, spades, hearts and a Liberty Bell; the bell gave the machine its name. By replacing ten cards with five symbols and using three reels instead of five drums, the complexity of reading a win was considerably reduced, allowing Fey to design an effective automatic payout mechanism. Three bells in a row produced the biggest payoff, ten nickels (50¢). Liberty Bell was a huge success and spawned a thriving mechanical gaming device industry. After a few years, the devices were banned in California, but Fey still could not keep up with the demand for them elsewhere. The Liberty Bell machine was so popular that it was copied by many slot machine manufacturers. The first of these, also called the "Liberty Bell", was produced by the manufacturer Herbert Mills in 1907. By 1908, "bell" machines had been installed in cigar stores, brothels and barber shops. Early machines, including an 1899 Liberty Bell, are now part of the Nevada State Museum's Fey Collection.

The first Liberty Bell machines produced by Mills used the same symbols on the reels as did Charles Fey's original. Soon afterward, another version was produced with patriotic symbols, such as flags and wreaths, on the wheels. Later, a similar machine called the Operator's Bell was produced that included the option of adding a gum-vending attachment. As the gum offered was fruit-flavored, fruit symbols were placed on the reels: lemons, cherries, oranges and plums. A bell was retained, and a picture of a stick of Bell-Fruit Gum, the origin of the bar symbol, was also present. This set of symbols proved highly popular and was used by other companies that began to make their own slot machines: Caille, Watling, Jennings and Pace.