Dark data is the untapped information stored but not actively used—often making...

https://www.wall-bookmarkings.win/dark-data-refers-to-the-55-of-stored-information-that-businesses-collect-but

Dark data is the untapped information stored but not actively used—often making up 55% of enterprise data. It drives up storage and backup costs and increases breach risk since unmanaged data is more vulnerable to ransomware