Information, as what we we may read, sense, perceive, or see, could be easily disappear due to the vaporizing of its medium, or just unretrievable by losing the links between subjective and them. I call this phenomenon "Information Dust".
Many efforts, like Internet Archive, strive to keep human information as much as they can. However, it's unavoidable to lose more and more as we create them more and more. Some information may become Information Dust because of their less relevance. Some other information dust maybe important from either itself, or the connections between other information.