The numbering of book editions is a special case of the wider field of revision control. The traditional conventions for numbering book editions evolved spontaneously for several centuries before any greater applied science of revision control became important to humanity, which did not occur until the era of widespread computing had arrived (when software and electronic publishing came into existence). The old and new aspects of book edition numbering (from before and since the advent of computing) are discussed below.
 First edition
According to the definition of edition above, a book printed today, by the same publisher, and from the same type as when it was first published, is still the first edition of that book to a bibliographer. However, book collectors generally use the term first edition to mean specifically the first print run of the first edition (aka "first edition, first impression"). Since World War II, books often include a number line (printer's key) that indicates the print run.
A "first edition" per se is not a valuable collectible book. A popular work may be published and reprinted over time by many publishers, and in a variety of formats. There will be a first edition of each, which the publisher may cite on the copyright page, such as: "First mass market paperback edition". The first edition of a facsimile reprint is the reprint publisher's first edition, but not the first edition of the work itself.
 Bibliographical definition
The classic explanation of edition was given by Fredson Bowers in Principles of Bibliographical Description (1949). Bowers wrote that an edition is “the whole number of copies printed at any time or times from substantially the same setting of type-pages,” including “all issues and variant states existing within its basic type-setting, as well as all impressions.”
Publishers often use the same typesetting for the hardcover and trade paperback versions of a book. These books have different covers, the title page and copyright page may differ, and the page margin sizes may differ (same type area, smaller trim), but to a bibliographer they are the same edition.
From time to time, readers may observe an error in the text (or, in the days of metal type, a piece of broken type), and report these to the publisher. The publisher typically keeps these reprint corrections in a file pending demand for a new print run of the edition, and before the new run is printed, they will be entered.
The method of entry, obviously, depends on the method of typesetting. For letterpress metal, it typically meant resetting a few characters or a line or two. For Linotype, it meant casting a new line for any line with a change in it. With film, it involved cutting out a bit of the film and inserting a new bit. In an electronic file, it means entering the changes digitally.
Such minor changes do not constitute a new edition, but introduce typographical variations within an edition, which are of interest to collectors.
 Collectors' definition
A common complaint of book collectors is that the bibliographer's definition is used in a book-collecting context. For example, J. D. Salinger's The Catcher in the Rye remains in print in hardcover. The type is the same as the 1951 first printing, therefore all hardcover copies are, for the bibliographer, the first edition. Collectors would use the term for the first printing only.
First edition most often refers to the first commercial publication of a work between its own covers, even if it was first printed in a periodical: the complete text of Ernest Hemingway’s The Old Man and the Sea appeared in the September 1, 1952 issue of Life magazine, yet the generally accepted “first” edition is the hardcover book Scribner’s published on September 8, 1952.
The term "first trade edition," refers to the earliest edition of a book offered for sale to the general public in book stores. For example, Upton Sinclair's 1906 novel The Jungle was published in two variant forms. A "Sustainers' Edition", published by the Jungle Publishing Company, was sent to subscribers who had advanced funds to Sinclair. The first trade edition was published by Doubleday, Page to be sold in bookstores.
A small minority of book collectors, particularly in the science fiction field, hold that the earliest bound copies of a book—promotional advance copies: bound galleys, uncorrected proofs, advance reading copies sent by publishers to book reviewers and booksellers—are the true first edition.
 Publishers' definition
Publishers use the term first edition for their own purposes, with little consistency. The "first edition" of a trade book may be the first edition by the current publisher, or the first edition with a particular set of illustrations or editorial commentary.
Non-fiction, academic and textbook publishers generally distinguish between revisions of the text, usually citing the dates of the first and latest editions on the copyright page. However, even this rule of thumb is sometimes bent. A new textbook with a different format, title, and authors may be called a "second edition" because a previous textbook is being counted as the first, despite being essentially a different book (sharing only the subject with the new one). This stretch of the definition is done for its marketing effect, because the new textbook may seem more authoritative to the potential buyer if it implies that there have been "previous editions".
 Revised edition
The terms revised edition and nth edition, revised are sometimes used by publishers when the book has been editorially revised or updated but for some reason the author or publisher does not want to call it the n+1th edition (where n = previous edition number).
Conversely, they may decide to call a version that is really not very different a "new edition" (n+1th).
The qualitative difference, then, between a "revised edition" and a "new edition" is subjective. This is analogous to the way that software publishers may call one update "version 3.7" but call the next update "version 4" instead of "version 3.8". The difference is their subjective sense of the significance of the change—that is, whether the differences constitute something very different or merely slightly different. Sometimes the distinction has more to do with marketing than with sound reasoning (that is, encouraging buyers to think that something slightly different is very different).
The basic definition of a co-edition is when two publishing houses publish the same edition of a book (or equivalent versions of an edition, for example, translated versions), simultaneously or near-simultaneously, usually in different countries. Engilsh and American editions may differ in spelling. Some examples:
- An English-language edition, from the same plates, films, or files, may be published in different anglophone countries by different publishing companies. For example, Arms & Armour Press in the UK and Stackpole Books in the U.S. published co-editions of various monographs on military matters.
- A French-language novel published in France this year by a French publisher could become an English-language translation published in the U.S. next year by a U.S. publisher.
The logic of co-editions has often been to use the existing distribution systems of the different publishers in each country rather than establishing new distribution systems.
Advancing IT and the globalization of publishing have been blurring the lines of what co-edition means. For example, anything published online is effectively published worldwide. Also, large multinational publishers now have existing distribution systems for their hardcopy books in many countries, so they don't need to partner with other companies. They may issue a book under a different imprint for each country, but the imprints are parts of the same parent corporation. The actual manufacturing of the books may be done in China regardless of where the copies will be sold.
The term e-dition, a play on the e-for-electronic prefix, has been used by various publishers to refer to various ideas, which include:
- The hardcopy book's content posted online, fully searchable
- Supplemental online-only content for buyers of the hardcopy book
- Online-only publishing (no hardcopy distribution)
- Proprietary-format digital publication (e-books) for use in specialized hardware for reading the book (e-book readers)
 Library Edition
A library edition may appear to be the same as copies appearing in shops and almost certainly uses the same setting. However the binding and hinges are made extra strong to allow for the greater wear and tear in library books.
 Book Club Edition
A popular book is sometimes re-issued under the imprint of a book club. Often it is a new setting and with cheaper paper and binding. Any photographic illustrations in the original are either absent or reduced in number. Book club editions are sold to members at a good discount compared with the original issue price.
 Cheap Edition
After a book has exhausted the market at the high original price a publisher may issue a cheap edition themselves or sell the rights on to another publisher who will produce the book. A cheap edition typically uses a low cost paper and is a paperback but they can be hardback. Also typically the size of the font is reduced to fit more words on a page to reduce the overall cost of the book. Naturally for a cheap edition the author will receive a lower royalty but that may be compensated for by a greater volume of sales.
 Cadet Edition
A cadet edition is a cut down version of a book which is more simply written. It is intended for young readers rather than adults.
 Large Print Edition
These editions are typically library editions but the font size of the text is much larger than usual so that persons with poor eyesight (often older persons) can more easily read the book. The large print books tend to be of a uniform size.
 Colonial Edition
During the peak of the British Empire, cheap editions of novels published in Britain would often be produced for sale in the colonies before other editions of the books were sold. The rationale was that books took a long time to export to the colonies, that readership in those settlements was avid, and that books were an effective means to disseminate British values. Australia was by far the largest consumer of colonial editions. Macmillan (London) published the largest number of colonial edition titles. They began in 1843 and persisted (in terms of pricing and trade) until the 1970s. They are no longer produced. Their history has been chronicled in 
 Revised and Updated Editions
When a non-fiction book is first published it sometimes generates more research on the topic. The author may find that in the light of the new information the book needs to be revised and updated. The new edition will thus be different from the earlier one and will therefore be a new edition. The second edition may not necessarily be published by the same publisher as the original. Years may pass between the two editions.
 Print run
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Each batch of copies printed is termed a print run, printing run, printing, impression, or press run. This is all of the copies produced by a single set-up of the production equipment. One edition can have any number of print runs. Poor-selling books may have only one. Very successful books may have 50 or more.
A publisher hopes to recoup a large amount of the book's initial costs from the sale of the book's first print run. A variety of commercial and logistic factors are thus considered in deciding the number of books in a print run, and their unit price.
Demand for additional print runs after the first is always hoped for, because they increase the book's overall profitability. Once the fixed costs of developing, editing, typesetting, etc., have been covered by the first sales revenue, any additional sales revenue tends to add to the profit margin (minus, of course, the costs of the additional materials, printing, binding, and distribution).
Sometimes a print run will be unsatisfactory for some reason, particularly with art and photography books where reproduction quality is paramount. It is usually destroyed by being pulped, but occasionally a defective print run may be shipped to a distant overseas market and sold there cheaply, depending on shipping costs.
If sales of the book do not meet expectations, the remaining stock of a print run will be remaindered. When a print run is sold out, the title is either reprinted or becomes out of print. Some print on demand and e-book publishers keep all their titles perpetually in print.
Seconds are imperfect or damaged copies which are set aside from a print run. These will usually have their dust jacket clipped or marked in some way.
From time to time, readers may observe an error in the text and report these to the publisher. The publisher typically keeps these reprint corrections in a file pending demand for a new print run of the edition, and before the new run is printed, they will be entered. This is one of the factors that puts the "substantially" into the definition of "substantially the same setting of type".
Many commercially successful books have been republished, either by their original imprints or by other imprints. This explains why if you look up a popular book title at a large bookseller such as Amazon or a large library catalog such as WorldCat, you often find an array of different copyright years, publishers, editions, formats (hardcover, softcover, trade, mass market), and so forth. The exact distinctions between "reprinting" and "republishing" and on whether a republishing is or is not a "different edition" are not policed by any universal authority, so the meaning of the terms used in any instance cannot be known at first glance.
 Effect of technological change on the concept of "different versions"
The traditional concepts of versions of texts (editions, print runs, etc.) were shaped by the technology of printing on paper. As technology changes, the definitions of edition, co-edition, and print run are challenged by new models. For example, in the era of digital typesetting, print-on-demand, internet publishing, and e-books, how does one draw a line between different versions of the content? It can change every day, with any one instance of display (one hardcopy, one screen refresh, etc.) being different from the next. Yet the abstract distinctions of "big change" versus "little change" will probably continue to exist, simply taking new forms.
 Legal status
Since 1956, typographical arrangements of published editions are protected by copyright law. Copyright, Designs and Patents Act 1988 defines a published edition to mean a published edition of the whole or any part of one or more literary, dramatic or musical works.
It thus protects the publisher's investment in typesetting, as well as the processes of design and selection that are reflected in the appearance of the text. It also covers modern editions of public domain works (such as the complete works of Shakespeare), and prohibits the reproduction of the layout (but not the work itself).
 See also
- Editio princeps - essentially, the first printed edition of classical or medieval works
- Printers key
- Publication right
- Remaindered book
- Leventhal 2006.
- Graeme Johanson, 'A study of colonial editions in Australia, 1843-1972'. Elibank Press, Wellington, New Zealand. ISBN 0958349630.
- Duration Directive of the EU permits member states to create a publishers' right in critical and scientific works which have fallen into the public domain
- Newspaper Licensing Agency v. Marks & Spencer 
- Bowers, Fredson. Principles of Bibliographical Description, Winchester and New Castle, Delaware: St Paul's Bibliographies and Oak Knoll Press, 2005 (reprint edition, first published in 1949).
- Leventhal, Lionel (2006), On Publishing: A Professional Memoir, London: Greenhill Books, ISBN 978-1-85367-517-1
- Bookpoi.com official homepage — a comprehensive online guide to identify first edition, rare and collectible books.
- Edition state terminology
- First Edition Points Online Reference Guide is a free searchable database of points of issue for hundreds of modern first edition books. Includes images of cover, copyright page, dust jacket flaps, etc.
- How to Identify a First Edition
- Pulitzer Prize First Edition Guide is a free searchable database of first edition Pulitzer Prize for Fiction books. Includes images and points of issue.
- Terms from the Antiquarian Booksellers Association — see "Edition", "First Edition", "Impression", "Printing" etc.