Gambling terms, explained straight

Slots & Gaming Machines

Slot machine reels

Slot machine reels are the physical or virtual spinning components that display symbols and determine the outcome when they stop.

Also called
Reel-based games, fruit machines, jackpot machines
How they work
A random number for each reel maps to a stopping position on the reel strip, displaying a symbol combination57
Common configurations
3 reels or 5 reels, depending on the game67

Key points

  • Each spin is independent of prior spins; the outcome is determined by a random number for each reel7.
  • Reels are part of a slot machine, not the whole game — the machine includes the cabinet, software, and payout system2.
  • Regulators define slots as reel-based casino games, including those with non-traditional reels13.

Where this term is used

Not the same as

Slots Slot machine The complete gambling device or game that includes reels as one component. Slots 5 reel slot machine paylines The winning line patterns across a five-reel game, distinct from the reels themselves. Slots Slot machine jackpot The top prize awarded when a specific symbol combination lands on the reels. Slots Slot machine price The cost to buy or lease a slot machine, which houses the reels. Slots Slot machine payouts The amounts paid for winning reel combinations, determined by the paytable. Slots Cascading reels slots A variant where winning symbols disappear and new ones fall into place on the reels.

Sources

  1. Online games design and reverse withdrawals gamblingcommission.gov.uk Supports the definition of slots as reel-based games and the regulatory context.
  2. Gaming machine categories gamblingcommission.gov.uk Supports the distinction between a slot machine and its reels.
  3. Definitions of terms gamblingcommission.gov.uk Supports the inclusion of non-traditional reels in the definition.
  4. Full article: Losses disguised as wins in multiline slots tandfonline.com Supports the distinction between reels and paylines.
  5. Deconstructing Cleopatra wizardofodds.com Supports the random number mapping process for each reel.
  6. Deconstructing Jackpot Party wizardofodds.com Supports common reel configurations like 3 or 5 reels.
  7. Slot Machines wizardofodds.com Supports the core definition, independence of spins, and random number process.

Sources are drawn from regulators, universities and published research, and each one is labelled with what it actually is — a preprint is not called a paper. Bookmaker and affiliate pages are never cited here, because a page that sells betting is not a neutral authority on it.

Written and maintained by Ellis Warrender, writer and maintainer.

Last updated 28 July 2026. Spotted an error? Tell me and it gets fixed and logged on the corrections page.