Dark data is the inactive, unstructured information most companies don’t manage...

https://www.bookmark-xray.win/dark-data-is-the-information-organizations-collect-but-don-t-use-often-making

Dark data is the inactive, unstructured information most companies don’t manage well—often 55% of all stored data. This hidden data boosts storage and backup costs and raises risks like ransomware exposure or breaches