A record of an event or knowledge, taken so, that the information will not be lost.
Initially documents were usually written, but they could also be made up of images, figures, graphs or sounds. Documents can exist in hard copy or can be put into electronic or digital form, can be stored on a computer, media, drive, cloud or can be shared in different ways. The tendency is to use the term 'document' for any object (file) in a system, storage or portal.
An IAEA document on Accident Knowledge Taxonomy.