Shifting wilds, also known as walking wilds, are wild symbols that move across the reels from one spin to the next instead of disappearing after a single spin. Like ordinary wilds, they substitute for regular symbols to complete winning combinations. The difference is their movement: a shifting wild typically steps one reel or position in a set direction on each spin, often during respins or free spins, until it leaves the grid.
They sit between standard wilds and sticky wilds, which stay in one place, and some games combine the two or add multipliers to moving wilds. The exact path and duration differ from title to title, so the paytable is the place to check. For operators, wild mechanics like these make useful lobby tags, since many players search for games by feature.