A style of binding featuring a cover (leather, or other material, but customarily leather) that overlaps the three edges of both upper and lower covers continuously. The covers are always limp or semi-flexible, and are sometimes fitted with a zipper, which was a later refinement. Yapp books, named after the English bookseller of the second half of the 19th century, William Yapp, always have round corners, and the endpapers are frequently made from a "surface" paper, usually black. The edges are sometimes gilt, frequently over red, or are stained or otherwise colored. The Yapp style is especially associated with books of devotion (almost exclusively today), although a half century ago books of verse were sometimes bound in somewhat similar covers. See also: CIRCUIT EDGES .