Narrow strips of rawhide or processed animal skin, such as leather or alum-tawed skin, across the back of a book to which the sections were sewn early in the development of flexible sewing. Distinguished from "cords (binding components)" which are twisted strands of fibrous material that replaced thongs by the latter part of the 16th century, and from "tapes (binding components)" which are narrow strips of closely woven cloth serving the same purpose.
