Dark data is all the info a company collects but never uses—think emails, logs,...

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

Dark data is all the info a company collects but never uses—think emails, logs, or old documents. It can be as much as 60-80% of stored data. Ignoring this stuff wastes time and money—some firms lose up to $2.5 million a year on storage and management