Dark data is the information your team stores but rarely uses, often making up...

https://raymondsinterestingchat.quantlynix.com/posts/do-i-need-to-move-petabytes-to-the-cloud-to-get-value-from-dark-data

Dark data is the information your team stores but rarely uses, often making up 55% of all data. It takes up expensive space and can hide security risks