The word slot has a grammatical meaning and a wide variety of usages. In its original form, the word refers to a hollow in the throat above the breastbone. The word is from Old French esclot, from which its modern meaning derives. Its meaning also has its roots in the Old Norse slod. The term first appears in print in the 1520s, while the meaning of slot machine dates from 1888.
The basic idea of slot machines involves rotating mechanical reels. The first slot machine used five reels, but a simple three-reel slot machine proved to be more reliable. The initial versions of slot machines were based on simple math, and the odds of winning any symbol were the same regardless of the number of symbols on the reels. As a result, the payouts could be large, but were not as high as today. The original machines might have only three reels with 10 symbols on each. This meant that the jackpot could be as much as 1000 times the amount of money that a player bet.
In addition to video game machines, slot machines are also used in computers. The first fully electromechanical slot machine was developed in 1963 by Bally. The company had already used this technology in its draw-poker machine in 1940. Money Honey was another example. Its top-rated feature was an automatic payout of up to 500 coins. The popularity of Money Honey led to the increasing use of electronic machines and the side lever became a mere vestigial part.