Books are divided into hardback and paperback (or paperback). The so-called hardcover book generally refers to a book with a certain thickness, the cover and back cover and spine of cardboard or other special materials, the design, printing and packaging of more sophisticated large-scale books. The paperback is relative to the hardback, which is generally a small book album and product catalogue, etc., and its cover and back cover and spine are not processed with special materials. Other than that, there is not much difference between the two types of spine in terms of terminology and design specifications.
Relative to the opening number, it refers to the single-page area of the product of the book, which accounts for several fractions of the single-side area of the whole paper. It is customary to use the following paper specifications as the benchmark for various folios.
Small format: a book made of 787mm x 1092mm paper
Large format: a book made of 850mm x 1168mm paper
Jumbo: A book made of 880mm×1230mm paper
Supersize: a book made of 889mm×1194mm paper
