Dark data is the information companies collect but never use—often 60 to 80% of...

https://star-wiki.win/index.php/How_Do_I_Stop_Dark_Data_From_Coming_Back_After_Cleanup%3F

Dark data is the information companies collect but never use—often 60 to 80% of their stored data. It’s like having a cluttered attic filled with stuff that costs money to store but offers no value