Dark data refers to the 55% of enterprise data that is stored but never used....

https://mighty-wiki.win/index.php/How_Do_I_Move_Cold_Data_to_Cheaper_Storage_but_Keep_Access%3F

Dark data refers to the 55% of enterprise data that is stored but never used. This inactive data increases storage and backup costs and raises ransomware exposure since attackers often target overlooked files