A slot is a position within a group, series, sequence, etc.; also, a place or opening in a wall, door, etc., that allows for a rod or bar to pass through.

In a slot machine, a player inserts money (or, in “ticket-in, ticket-out” machines, a paper ticket with a barcode) into a slot and then activates the machine by pushing a lever or button. The reels then spin and stop to rearrange the symbols, and if the symbols line up on a payline, the player wins credits according to the machine‚Äôs paytable. The symbols vary from game to game, but classics include fruit, bells, and stylized lucky sevens.

Modern slot machines use microprocessors to assign different weights to each symbol on each reel. These computer programs can make it appear that a particular symbol is close to appearing on the payline, even though the probability of it actually occurring is much lower.

The amount of money that a slot machine pays out in winning combinations is called its volatility (or variance). Slots with a low volatility are more likely to pay out often and have smaller wins, while slots with a high volatility will pay out less frequently but when they do the amounts will be higher.