A slot machine (American English), unofficially the slots (Canadian English), fruit machine (British English), poker machine (or "pokies" in slang) (Australian English and New Zealand English) or merely slot, is a casino gambling machine with about three or much more reels which spin when a press button is pressed. Slot machines are also referred to as one-armed bandits due to the fact they were in the beginning worked by a handle on the side of the machine as an alternative to a press button on the front panel, and due to their capability to leave the gamer penniless. Numerous current machines continue to have a legacy lever along with the button.

Slot machines consist of a money detector that validates the coin or cash put to play. The machine pays off depending on patterns of symbols observable on the front of the machine when it puts a stop to. Current computer technological know-how has resulted in several variations on the slot machine principle. Slot machines are the most well-known gambling method in casino houses and represent about 70 % of the common US casino's revenue.

Bally created the first entirely electromechanical slot machine named Money Honey in 1963, despite the fact that previously machines just like the High Hand draw poker machine by Bally had displayed the fundamentals of electromechanical structure since 1940. The electromechanical technique of the 1960s permitted Money Honey to be the initial slot machine with a bottomless hopper and automatic pay out of around 500 coins without the need of the assist of a worker. The recognition of this machine resulted in the raising predominance of electronic games, and the side handle rapidly evolved into vestigial.

The initial real video slot machine was created in 1976 in an commercial suite in Kearney Mesa, CA by R. Greene, W. Beckman, N. Cerracchio,  J. Reukes, and L. Black within the direction of the Vegas dependent Fortune Coin Company. This slot machine made use of a revised 19" Sony Trinitron colour receiver for the exhibit and judgement boards for all slot machine characteristics. The model was installed in a 100 % size show-ready slot machine cabinet. The initial manufacturing units started test in the Vegas Hilton Hotel. Right after some cheat-proofing adjustments, the video slot machine was authorized by the Nevada State Gaming Commission and ultimately identified acceptance in the Las Vegas Strip and the town center casinos.  In 1978, Fortune Coin Company and their video slot machine technological innovation were bought by International Gaming Technology.

The initial United states video slot machine to supply a second screen bonus round was Reel 'Em In created by WMS Industries Incorporated in 1996. This form of machine had made an appearance in Australia from at the very least 1994 with the "Three Bags Full" game. In this kind of machine, the exhibit changes to supply a diverse game where an extra payout could possibly be accumulated or gained.