Octavo

An octavo (abbreviated 8vo) is a book size resulting from folding a standard-size sheet of paper three times to form eight leaves or sixteen pages. The dimensions of an octavo book are generally about 6 × 9 inches (15 × 23 cm), although this can vary depending on the original sheet size used.

The term "octavo" also refers to a book printed on octavo paper or, more generally, a book that is approximately this size. It is one of the common book sizes used for novels, biographies, and other general-interest books.

In descriptive bibliography, the term "octavo" indicates the format of the book, providing information about how the printed sheets were folded and gathered to form the book's structure. The imposition scheme used to create octavo books is more complex than for folio or quarto formats. Careful planning is needed to ensure that the pages are printed in the correct order when the sheet is folded.

Historically, the octavo format was associated with affordability and portability compared to larger formats like folio and quarto. It became a popular choice for publishing works intended for a wide readership.