Dark data is the hidden stash of inactive or unused info companies store...

https://apple-filament-2f5.notion.site/Dark-data-is-all-the-stored-info-companies-keep-but-rarely-use-think-55-of-3f7b95cd6dcd8032900afcdb0043d378

Dark data is the hidden stash of inactive or unused info companies store without knowing its value. Around 60% to 80% of data can sit inactive, costing money to keep and posing security risks