Dark data is all the information companies collect but don’t actively use—often...

https://www.bookmarkzoo.win/dark-data-is-the-inactive-or-unused-information-that-companies-keep-but-don-t

Dark data is all the information companies collect but don’t actively use—often 60-80% of stored data sits inactive. It matters because holding onto this unused data wastes space and can cost businesses millions yearly, sometimes up to $2.5 million