Dark data is the information your organization collects but doesn’t use, often...

https://victor-wiki.win/index.php/What_Does_It_Mean_to_Filter_Out_More_Than_70_Percent_Data_Noise%3F

Dark data is the information your organization collects but doesn’t use, often making up 55% of stored data. This inactive data increases storage and backup costs and raises the risk of ransomware attacks or breaches