Dark data is the information your company collects but never uses—think 60-80%...

https://station-wiki.win/index.php/Why_Does_Keeping_Dark_Data_on_Flash_Storage_Feel_Like_Burning_Money%3F

Dark data is the information your company collects but never uses—think 60-80% of your stored data lying dormant. It’s more than just digital clutter; keeping it can cost you around $2.5 million a year in storage, security risks, and lost opportunities