Dark data is the inactive or unused information your business stores but...

https://xeon-wiki.win/index.php/Dark_Data_and_AI_Hallucinations_%E2%80%93_Is_There_a_Connection%3F

Dark data is the inactive or unused information your business stores but doesn’t analyze, often making up 55% of all data. It creates real risks like increased ransomware exposure and drives up costs through wasted storage and backup resources