Dark data is the untouched information stored in your systems—up to 55% of all...

https://wiki-cable.win/index.php/Dark_Data_in_IoT_Environments_-_What_Should_We_Keep%3F

Dark data is the untouched information stored in your systems—up to 55% of all data goes unused. This matters because it racks up costs and creates risk, especially when AI sifts through cluttered files