Reels refers to the full set of spinning columns that makes up a slot game’s playing area. A standard video slot shows five reels with three rows of symbols each, but the set can be larger, uneven or even include a horizontal reel. Each reel runs a strip of symbols in a fixed order; when a spin starts, the reels move together and stop one by one, usually from left to right, to reveal the result.
Many slot features work by changing the reels themselves: cascading reels replace winning symbols with new ones, expanding reels add rows, respins hold some reels while the others spin again, and wilds can be stacked or held in place. Because these mechanics shape volatility and hit frequency, operators often group games by reel features in the lobby, and the paytable remains the place to check how each one behaves.