Dark data is the inactive information companies store but rarely use—often...

https://www.bestbookmarks.win/dark-data-is-all-the-stored-information-companies-keep-but-never-use-think-old

Dark data is the inactive information companies store but rarely use—often making up 60-80% of their data. It matters because keeping all that unused data costs money, sometimes up to $2.5 million a year