Dark data is the inactive information companies store but rarely use. It can be...

https://sierra-wiki.win/index.php/How_Does_Dark_Data_Increase_Inferencing_Costs_and_Token_Usage%3F

Dark data is the inactive information companies store but rarely use. It can be as much as 60-80% of all stored data. This unused data takes up space and costs businesses millions—sometimes $2.5 million annually—in storage and management