Dark data is all the info your company collects but never uses—sometimes 60 to...

https://cashsbrilliantperspectives.cavandoragh.org/what-is-dark-data-management-not-the-marketing-version

Dark data is all the info your company collects but never uses—sometimes 60 to 80% of it sits inactive. It matters because storing and managing this unused data can cost millions each year, often $2.5 million or more