Scatter symbols are one of the multitudes of different symbols we see in slots games, but they do have a few key roles and advantages.
Unlike normal slot symbols that have to be lined up on a pay line to win, the scatter can appear anywhere on the reels to activate the free spins, mini-games and other bonus games. Scatter symbols are one of the highest paying symbols in a slot game and are usually represent the theme that the slot is based on.
Usually, a particular amount of scatter symbols need to appear during spins to unlock one of the bonus features. When the required number appear on a single spin, the game will launch the bonus game. A majority of the time this is free spins, but sometimes they do trigger other bonus games as well as free spins.