Dark data is all the stored information companies keep but never use—think old...

https://charlie-wiki.win/index.php/What_is_a_Global_Metadatabase_and_Why_Would_I_Want_One%3F

Dark data is all the stored information companies keep but never use—think old files, logs, or emails piling up unnoticed. Surprisingly, 60-80% of data goes untouched, costing businesses around $2.5 million each year in storage and management