Blank symbols on online slots are symbols that do not have any value or payout associated with them. They are sometimes also referred to as "empty" or "dead" symbols.
Blank symbols are typically used to create gaps between other symbols on the reels, which can help to increase the suspense and excitement of the game. They can also be used to make it more difficult for players to achieve winning combinations, thereby increasing the level of challenge and making the game more engaging.
In some online slots, blank symbols may also have special features or functions. For example, they may act as wild symbols, which can substitute for any other symbol to create a winning combination. Alternatively, they may trigger bonus rounds or other special features when they appear on the reels.
Overall, blank symbols are just one of the many elements that contribute to the complexity and excitement of online slot games, and they are an important part of the overall game design.