Dark data is the information organizations collect but don’t use, making up 55%...

https://romeo-wiki.win/index.php/Why_Does_Dark_Data_Create_Operational_Drag_for_IT_Teams%3F

Dark data is the information organizations collect but don’t use, making up 55% of stored data on average. This unused data increases storage and backup costs and raises the risk of ransomware or data breaches