Dark data is the unused info hiding in your systems—think old emails, unused...

https://www.first-bookmarkings.win/dark-data-is-the-inactive-or-hidden-information-lurking-in-your-storage-often

Dark data is the unused info hiding in your systems—think old emails, unused files, and forgotten docs. Around 55% of data stored falls into this category, silently increasing storage costs and security risks