The slot machine is a casino game in which players place bets with cash or, in “ticket-in, ticket-out” machines, paper tickets with barcodes. The machine then activates a series of reels that spin and stop to rearrange symbols in order to produce winning combinations. Winning combinations award credits based on the paytable, and are displayed on a video screen. Symbols vary by theme, but classic icons include fruits, bells, and stylized lucky sevens.
During the 1960s, when slots were first becoming popular, manufacturers tried to prevent cheating by making it difficult to replace coins in the machine. The top of the slot had a metal shaft that connected to the handle mechanism; a coin detector detected a coin’s presence and unlocked a brake that kept the reels from spinning, while sensors communicated the position of the reels to the payout system.
As technology improved, manufacturers began incorporating microprocessors into their machines. These allowed them to program each reel with different probabilities for the various symbols. This made it more difficult for cheaters to replace coins, because a new coin would appear with a different probability on the reels than the old one.
The modern electronic designs of slot machines are more complicated, but the basic concept remains the same: a player pulls a handle to rotate a group of reels that have pictures printed on them. If the symbols line up with a pay line that runs vertically down the center of the window, the player wins (certain single images are also winners). The amount won depends on how many of the symbols land on the pay line.