Dark data is the info companies collect but don’t use, often making up 60-80%...

https://star-wiki.win/index.php/Should_I_Prioritize_Tiering_Cold_Data_or_Scanning_for_PII_First%3F

Dark data is the info companies collect but don’t use, often making up 60-80% of their stored data. It matters because keeping this inactive data costs money—some businesses waste up to $2.5 million a year on storage and management