Dark data is all the information companies collect but never use—like old files...

https://www.bright-bookmarks.win/dark-data-is-the-information-your-organization-collects-but-doesn-t-use-often

Dark data is all the information companies collect but never use—like old files and logs. It makes up 60-80% of stored data and can cost businesses up to $2.5 million a year just to keep