Dark data is the inactive or unused information sitting untouched in your...

https://speedy-wiki.win/index.php/How_Does_Dark_Data_Make_AI_Answers_Worse%3F

Dark data is the inactive or unused information sitting untouched in your systems—often making up 60%-80% of your stored files. It matters because it wastes space, drives up costs, and creates noise that can confuse AI projects