Librarians define "document" as “materially fixed knowledge […] capable of being used for consultation, study, and proof”.¹

Some documents are published (e.g. a magazine article), while other documents are unpublished (e.g. a letter). Unpublished documents are more often found in other types of repositories, like archives. Archives are sometimes attached organizationally to libraries. For example, the University Archives, and the Student Life and Culture Archive are both units within the University of Illinois Library. The Champaign County Historical Archives is a unit within the Urbana Free Library.

Libraries typically collected published documents. The fact of publication, therefore, is an essential concept for researchers who wish to be skillful users of libraries.

When new technologies for producing documents become available, the producers of documents tend to imitate the formal properties that characterized documents produced by earlier technologies.

For example, early printed books resembled handwritten manuscripts, most notably in the use of typefaces that resembled handwriting. Early printers also used hand-colored woodcuts that were supposed to look like illuminations, and elaborately ornamented drop initials.²

Below are two examples: the first page is from a book produced by hand, using pen and ink; the second page is from a book produced by machine using movable type and printing press.

15th Century Manuscript (ca. 1450)

15th Century Printed Book (ca. 1488)

Only a specialist could easily distinguish the manuscript page from the printed book page.

Just as manuscript books preceded printed books, and printed books originally imitated manuscript books, so too did printed books precede periodicals, and in many respects periodicals began by imitating books.

Periodicals were originally treated as a kind of book published in parts, over a period of time.

Here is page two of the British Critic for February, 1794:

.

Note that the page more closely resembles that of a book than of periodicals, which are usually set in multiple columns. Note also the page  number is 122, even though it is actually the second page of the issue. This is because the pages for each volume (usually a calendar year, or half a calendar year) were numbered continuously, with the idea that, at the end of the year, the separate issues would be assembled and bound together as a single volume

When all issues of the volume had been published, the publishers included a book-like title page, preface, and even an index, with the idea that the whole thing would be assembled together, bound, and presented as a kind of book:

Popular periodicals eventually dropped this homage to the book, but academic journals have clung much longer to these formal conventions.

In citations for academic journals, the volume and issue numbering remain essential features (volume and issue number highlighted in yellow):

Kunzel, Regina. "Queer History, Mad History, and the Politics of Health." American Quarterly 69, no. 2 (June 2017): 315-319.

While for popular periodicals, the numbering is omitted:

Conant, Eve. "Do Ask, Do Tell." Newsweek, October 4, 2010.

We are going through a similar period now, where, despite the new possibilities afforded by online publication, traditional document genres like books and journal articles continue to resemble their print and paper antecedents.

Publication is the mechanical reproduction of a document into multiple copies, and the offering of those copies to the public (usually for sale).³

The two main types of publications collected by libraries are:

1. Books
2. Periodicals

1. Suzanne Briet, What is Documentation? trans. and ed. Ronald E. Day and Laurent Martinet (Lanham, Md.: Scarecrow, 2006).

2. Margaret M. Smith, "The Design Relationship between the Manuscript and the Incunable," in A Millennium of the Book: Production, Design, and Illustration in Manuscript and Print, 900-1900, ed. Robin Myers and Michael Harris (New Castle, Del.: Oak Knoll Press, 1994), 23-43.

3. Mary C. Turner, The Bookman's Glossary, 4th ed. rev. and enl. (New York, N.Y. : R.R. Bowker, 1961); John Carter and Nicolas Barker, ABC for Book Collectors, 9th ed. (London: British Library, 2004).