Modern slots are often associated with expanding grids, animated bonus rounds, multipliers, and complex reel systems. Yet two of the most recognizable slot mechanics come from much older machines: the nudge and the hold.
Both features create a brief pause in the normal spin cycle. Instead of every reel simply stopping and the next spin starting immediately, the game may allow part of the layout to move again or remain in place. That small change can make the experience feel more interactive without changing the fact that the game is still governed by its programmed rules and random outcome system.