Dark data is the information companies collect and store but never use—often...

https://wiki-room.win/index.php/What_Is_the_Difference_Between_Data_Catalog_and_File_Metadata_Index%3F

Dark data is the information companies collect and store but never use—often 55% of all data. This unused data creates storage and backup costs while increasing breach risk, especially ransomware attacks targeting overlooked files