Dark data is the inactive or unused information that piles up over time—often...

https://reidyxab469.iamarrows.com/do-i-have-to-move-petabytes-before-i-know-what-i-have

Dark data is the inactive or unused information that piles up over time—often making up 55% of storage. It increases your risk of ransomware attacks and bloats backup costs, sometimes costing businesses over $2.5 million annually