All copies of a book or e-book which share substantially the same content and presentation.
On one hand, the text is identical. On the other hand, the features offered by each file format may vary, thus changing the reading experience in a substantial way.
In addition, the ability to frequently revise an e-book at low cost has blurred the lines between a trivial change and a substantive change, making edition labelling more subjective.
In print publishing, one edition of a book may be produced over multiple print runs. So long as only minor typographical corrections are made, all of these copies would collectively be considered part of the same edition of the book.
In all types of publishing, the use of edition numbers, edition names, and the term "new edition" do not follow any standard rules.
These edition labels are sometimes manipulated for promotional or sales purposes. (For example, to imply that a new edition ought to be purchased to replace a previous one, or to generate added excitement, or to justify a high price for a "collector's" edition.)