What Is a Slot?

A narrow opening, hole, groove, or slit: a mail slot in the door; a cigarette lighter slot on the dashboard; a place for a coin in a vending machine. Also: (informal) a position in a group, series, or sequence: She slotted the book into her reading pile.

On older electromechanical slot machines, a slot was a hole in the front panel that allowed a technician to view the reels and the coin-in/ coin-out sensor. Modern slot machines use microprocessors and electronic components to determine if a spin is valid. The slots still allow access to the coin or ticket slot and display information on jackpot amounts, but this is usually only visible when the machine is turned off or in diagnostic mode.

Depending on the game, a slot may also include information on the theme, rules, and bonuses. This information is often highly abbreviated, as space is limited on a display screen. In some cases, especially on touchscreen displays, the slot information is presented in a series of images that can be switched between to reveal the full list of possible combinations and payouts.

When playing a slot machine, the player inserts cash or, in “ticket-in, ticket-out” machines, a paper ticket with a barcode. The machine then activates reels that can rearrange symbols and award credits based on the pay table. The symbols vary by machine and can include classic icons such as fruits, bells, and stylized lucky sevens.