Dark data is the inactive or unused information your company stores but doesn’t...

https://seo.edu.rs/blog/dark-data-risks-what-security-teams-worry-about-11142

Dark data is the inactive or unused information your company stores but doesn’t analyze or manage. It can make up 60-80% of your data, leading to wasted storage and backup costs. Plus, it increases your risk of ransomware attacks and data breaches