Dark data refers to the inactive or unstructured information stored but not...

https://garrettsbestblogs.theglensecret.com/is-dark-data-ever-worth-monetizing-or-should-i-just-delete-it

Dark data refers to the inactive or unstructured information stored but not used, often making up 55% of enterprise datasets. It increases storage and backup costs and exposes your systems to ransomware and breach risks