Your digital photos, letters, books, articles, documents, messages, etc. have no existence unless you pay attention to their preservation – or without electricity, for that matter. (You can’t really hold Zeros and Ones, Nothingness if you will, in your hands, let alone bequeath Nothingness to your heirs without taking serious steps to preserve and authenticate the data.)
See, e.g. from Moritz Law Library at The Ohio State University for what PURLs are: