Dark data is the information companies collect but don’t use—like old files or...

https://www.bookmark-tango.win/dark-data-is-the-unused-information-stored-in-your-systems-often-making-up-55

Dark data is the information companies collect but don’t use—like old files or unused emails. It can be a big problem because 55% of stored data falls into this category, leading to wasted storage costs and security risks