Three contributions are made to understanding the nature of documents. A survey of definitions of "document" from the last century shows that those definitions which most accurately reflect the ways in which the term "document" is used in practice are typically compound definitions, consisting of two or three elements that each refer to a different function of documents: medium, message, and meaning. Locating documents in E. J. Lowe's four-category ontology results in consideration of documents as universals rather than as particulars. Analysis of B. Smith's theory of document acts suggest that all documents, not just the ones that are involved in declarations, are creative in the special sense that they are generative of quasi-abstract entities of the kind that collectively comprise social reality.