First, divides according to the spine, spine of the square back and round two.

1, square back, its thickness is thicker than the book. Due to core collapse and cause a cable line, the height of the spine than the book, more copies, the more obvious. Therefore, the square spine hardcover books should not be too thick, generally applies to 20mm of the spine.

2, round spine, before and after the book are slightly different, book fold is slightly arched, located in an arc on the surface, the thickness of a balance. At the mouth of the book fit the cabochon and spine, concave in the round. So thick rounded spines of books is good. Rounding is a grilled round back after processing a circular-arc, usually a book block thickness to chord and the arc is 130 °. Rounding can be divided into the round back without Ridge (grilled round ridges) and circle back Ridge (grilled round ridges, Ridge height General and case-cardboard thickness) in two ways.

Second, according to the material, can be divided into ridges and ridged surface two different materials.

1, ridged surface with materials, namely, spine and cover the entire piece of the same material. Ridges and ridged in two ways. Hardcover fabric paper, such as paper, cloth, fabric, paint, is equipped with a dust jacket. However, there is a paper printed with the title, pattern on cardboard and laminated paper, such books were right with no dust jacket.

2, Ridge the same material, namely, spine and cover made from different materials, usually in the spine of the fabric, to paper over the paper on a hard paper cover, this form more commonly circular Ridge with no dust jacket.