The Book Block is the main body of the book, made by sewing together the segments. The segments, or folios Are the individual pages, which are collated, then folded and then sewn onto thecords
The Cords Are very often leather thongs and strengthen thespine.These are then laced into the boards The Boards form the rigid outer cover, and in early books are made from either wood or leather, (modern books use pasteboard).
The Spine Early books were bound with “tight” spines which form a concave hollow when opened. Later bindings use a “hollow” spine which is designed to keep a rounded shape at all times Example from a 15th Century Annunciation.