A narrow notch or groove into which something can be fitted, as a keyway in a lock or the slit for a coin in a vending machine. Also, a position in a group, series, or sequence, as in a schedule or timetable. See also berth, billet, niche, place, slot, window.

In a slot game, players insert cash or, in “ticket-in, ticket-out” machines, paper tickets with barcodes into a designated slot on the machine. Then the machine activates reels that spin and stop to rearrange symbols. When a winning combination appears, the player earns credits according to the paytable. The number and types of symbols vary by game; classics include fruits, bells, and stylized lucky sevens. Some slots allow players to choose which or how many paylines to wager on, while others automatically wage on all available paylines.

The term slot may also refer to a position on the field, as in ice hockey. The spot closest to the center of the face-off circles is often assigned to a defensive specialist called a slot receiver, who is responsible for blocking the defense and allowing other wide receivers to gain separation.

The probability that a particular symbol will appear on a payline is determined by its frequency on the physical reels and its weighting by the microprocessor inside the slot machine. This means that a symbol appearing on the first reel, for example, has a much higher chance of being hit than a symbol on the last reel, which is why some slot games can seem unfair.