Dark data is the inactive or unused information companies hold onto—about...

https://domgodwinson38.gumroad.com/p/what-should-i-do-with-former-employee-folders-on-the-file-server

Dark data is the inactive or unused information companies hold onto—about 60-80% of stored data. It matters because it increases storage and backup costs and exposes organizations to higher ransomware and breach risks