In gambling, a Slot is an opening that accepts something (such as a coin or a card) and pays out according to its paytable. A Slot can also refer to a position in a group, series or sequence, such as when a person is “slotted” into the first available chair.
Charles Fey’s 1887 invention of a mechanical slot machine was a significant improvement over the Sittman and Pitt poker machines that were already popular in the United States. Fey’s machine had three reels instead of two, allowed automatic payouts and featured symbols such as diamonds, spades, horseshoes, hearts and liberty bells—three aligned Liberty Bells was the highest win. These improvements helped the slots become more popular.
With the introduction of video slots in the 1980s, developers incorporated technology that weighted individual symbols differently on each reel. So, it wasn’t as easy to hit a jackpot as it had been on electromechanical machines. But even when the number of symbols was increased to 22—allowing for 10,648 possible combinations—the odds remained poorer for getting those higher-paying symbols, because they appeared less often on each reel.
Since that time, game designers have sought to understand what makes a slot attractive enough for players to keep playing it. Many manufacturers have leaned on data analytics firms, like ReelMetrics, to help them figure out what features keep people seated longer and generating the most revenue for casinos. Some of these factors are the frequency with which a player wins or loses, the total amount won and the percentage of time spent in the machine.