Fundamentally, a slot machine is a device with three spinning wheels covered in icons that is started with a lever on the side of the device or buttons on the front. When these wheels are stopped, the icons occasionally match up in groups of three horizontally or diagonally. If this happens, the player will win an amount of money determined by the icons and the device. "7"s and "Bar" icons usually pay out the most with fruit icons scoring lesser payouts, but many devices will use icons based around a theme instead (such as Halloween or Ancient Rome, or a video game or movie franchise). Some devices allow the player to fix wheels in place, or nudge them a certain number of times for a preferential configuration, though these bonuses usually have to be earned first.
Appearances in Video Games
Slot machines are frequently used in video games that simulate gambling and casinos. The Japanese equivalent Pachi-Slot are so popular that they have entire games dedicated to them alone, with series like Jissen Pachi-Slot Hisshouhou having dozens of entries.
Slot machines can also be used as a form of bonus stage to earn extra lives (as is the case in Super Mario Bros. 2) or as part of a stage/area themselves (as is the case in Sonic the Hedgehog 2's Casino Zone). In Borderlands 2, a slot machine in the hub town of Sanctuary can be played for random weapons and other valuables. Slot machines can also factor into the attacks of bosses or playable characters: the latter is especially prevalent in the Final Fantasy franchise - Wakka (Final Fantasy X), Selphie (Final Fantasy VIII) and Setzer (Final Fantasy VI) all use a slot machine interface as part of their limit breaks.
Often slot machines are just in an area as dressing and cannot be played, but can be destroyed for the money they contain.