Dark data is the inactive or unused information sitting untouched in your...

https://victoriasmasterchat.yousher.com/what-happened-in-the-ico-law-firm-cyber-attack-fine

Dark data is the inactive or unused information sitting untouched in your systems—often making up 60%-80% of your stored files. It matters because it wastes space, drives up costs, and creates noise that can confuse AI projects