Dark data is all the information your team collects but never uses, making up...

https://yenkee-wiki.win/index.php/What_Is_%E2%80%9COrphaned_Data%E2%80%9D_and_How_Do_I_Find_It%3F

Dark data is all the information your team collects but never uses, making up about 55% of stored data. It can quietly rack up storage costs and create security risks