When you "delete" a file, you aren't actually erasing the box from the warehouse. You are simply telling the librarian to rip up the index card that points to that box. The data sits there, invisible and ignored, until new data is written over it. (This is why specialized software can often recover "deleted" files).
In stationery, a (or report cover) is a plastic or cardboard folder used to organize and present documents. The Unsung Heroes of the Digital World: Understanding
: Contain information meant to be opened by other programs. Plain Text : Unformatted characters (e.g., .txt , .csv ). invisible and ignored