Dark data refers to information your company collects but never uses—often...

https://www.bookmark-help.win/dark-data-is-the-inactive-or-unused-information-that-sits-in-your-storage-often

Dark data refers to information your company collects but never uses—often making up 55% of stored files. This unused data takes up space, drives up storage and backup costs, and increases ransomware risk since it’s often unmonitored