Dark data is the information companies collect but never use or classify—often...

https://record-wiki.win/index.php/What_Should_We_Delete_First_When_Cleaning_Up_Dark_Data%3F

Dark data is the information companies collect but never use or classify—often 55% of all stored data. This unused data not only racks up storage costs, sometimes wasting over $2.5 million annually, but also creates risks like security gaps