A slot is a position in a sequence or series: Her TV show is in the eight o’clock slot on Thursdays. It can also refer to a place or time: We’ve slotted him for a four o’clock meeting. A slot is also a narrow opening, a slit or notch: The primaries of the wings of certain birds have slots that help maintain the flow of air during flight.
Originally, all slot machines used revolving mechanical reels to display symbols and determine results. The number of symbols on each reel limited jackpot sizes because a single symbol could only occupy one stop on the reel, giving it a cubic probability of appearing. Manufacturers then began to incorporate electronics, and the ability to weight symbols differently. This allowed a single symbol to appear multiple times on the payline, with different probabilities.
In modern slot machines, the player inserts cash (or, in “ticket-in, ticket-out” machines, a paper ticket with a barcode) into a designated slot to activate the machine. A reel then spins to rearrange the symbols, and a payline—a horizontal, vertical, diagonal or zigzag pattern of specific symbols—awards credits based on the payout schedule in the machine’s paytable. Today’s games offer many possible combinations of paylines and symbols, each aligned with a particular theme.
A slot attendant may use a service button on a slot machine to signal a player that he or she needs help, hand pay is required, or that there’s a problem with the machine. Depending on the game, this button may also be used to reset a progressive jackpot or unlock an extra bonus feature.