“Dark data” may sound like a magical element thought up by J.K. Rowling, but the risks associated with this type of information are very real for companies hosting it.

Dark data is data organizations keep unknowingly, according to James Sherer, an attorney at Baker Hostetler attorney specializing in data security and information governance. It has a cousin dubbed “dusty data,” the kind of information an organization kind of knows about, but is still cloaked with mystery and obscured by time, Sherer writes for JD Supra.