A slot is a machine that pays out credits for combinations of symbols that line up on a payline. In most slot machines, a winning combination involves three or more identical symbols.

The winning combinations are determined by a computer inside the machine called the MPU. This computer controls the actual reels and the theoretical pay out percentage of the game, as well as rejecting invalid coins.

High tech stepper motors operate the reels, which spin in response to a signal from the MPU. These high-speed stepper motors are similar to those used in space vehicles.

Coin recognition software is a vital part of the machine that checks the coin before each spin. The computer also tracks the number of coins in each bank and how many coins have been won.

Scam artists have tried to defraud slot players for years. In the early days, they would place magnets on the reels and remove them only when the machine had aligned the reels in a winning combination.

Modern machines employ magnetic and electronic sensors to detect the position of each of the reels. In addition, they have an MPU control board that allows the physical reels to rotate and pay out.

Jackpot

A jackpot is the biggest prize a slot machine or video slot offers, usually in the form of a progressive jackpot. The size of a jackpot depends on the type of slot.