Dark data is the inactive or unused information companies hold onto—about...

https://astro-wiki.win/index.php/Is_It_True_55_Percent_of_Enterprise_Data_Is_Dark%3F_Exploring_Dark_Data_Statistics_in_2025

Dark data is the inactive or unused information companies hold onto—about 60-80% of stored data. It matters because it increases storage and backup costs and exposes organizations to higher ransomware and breach risks