difference between file and a document

Question

I was reading a book on Portable Document Format. There were two headings, file structure and document structure. What is the difference between a file and a document? Are they not one and the same?

Solution

a file is a named collection of information that is recorded on some kind of storage device, while a document is a type of file that has been created by a particular software application, and can be manipulated by that application (e.g. a word processing document). A file can be a document, or it can be a program, or other types of data.