book size resulting from folded a sheets to make eight leaves
Book size These various production methods are referred to as the format of the book. These terms are often abbreviated, using 4to for quarto, 8vo for octavo, and so on. The octavo format, with eight leaves per gathering, has half the page size of the quarto format before trimming. Smaller formats include the duodecimo (or twelvemo), with twelve leaves per sheet and pages one-third the size of the quarto format, and the sextodecimo (or sixteenmo), with sixteen leaves per sheet, half the size of the octavo format and one quarter the size of the quarto. The vast majority of books were printed in the folio, quarto, octavo or duodecimo formats.[4]:82
International Standard Book Number An ISBN is assigned to each edition and variation (except reprintings) of a book. For example, an e-book, a paperback and a hardcover edition of the same book would each have a different ISBN. The ISBN is 13 digits long if assigned on or after 1 January 2007, and 10 digits long if assigned before 2007. The method of assigning an ISBN is nation-based and varies from country to country, often depending on how large the publishing industry is within a country.