Expanding wilds is a gambling term that describes a bonus feature that appears in slot machines and video slot games.
As you may know, wild symbols can substitute for every other symbol, allowing players to land winning combinations much more easily. Unless they are purposely designed to resemble classic video slots, virtually every modern-day video slot comes with wild symbols and bonus features. Some of those video slots include the expanding wilds feature, which once triggered, causes wild symbols to expand.
Depending on the design of a video slot, wild symbols can expand to cover an entire reel, or they can expand in a pattern specified by the software developer that produced the game.
Most often, expanding wilds are triggered randomly whenever there is a wild symbol present on the reels, meaning you can’t do much to affect the feature. However, if you are lucky enough, this feature can help you form several winning combinations and substantially increase the amount you can win.