Dark data is the information companies collect but never use—up to 80% of data...

https://charlie-wiki.win/index.php/What_is_a_Global_Metadatabase_and_Why_Would_I_Want_One%3F

Dark data is the information companies collect but never use—up to 80% of data sits idle and hidden. This unused data can cost businesses millions each year, often around $2.5 million wasted on storage and management