Dark data is the unused information sitting in your servers and storage—about...

https://zandersexcellentblog.quillnesty.com/posts/why-does-dark-data-make-search-results-noisy-inside-the-company

Dark data is the unused information sitting in your servers and storage—about 55% of data companies hold stays untouched. It matters because it drives up costs, creates security risks, and clutters AI projects with irrelevant noise