Dark data is all the information your company collects but never really uses....

https://www.cool-bookmarks.win/dark-data-is-the-inactive-or-unseen-information-companies-keep-but-don-t-use

Dark data is all the information your company collects but never really uses. It could be 60-80% of your stored data just sitting idle. This unused data costs businesses around $2.5 million every year in storage and management expenses