Dark data is the unused information stored in your systems, often making up 55%...

https://www.active-bookmarks.win/dark-data-is-the-information-your-organization-collects-but-never-uses-often

Dark data is the unused information stored in your systems, often making up 55% of all data. It can expose your organization to ransomware attacks and breach risks since it’s unmanaged and unmonitored