If you have a high-quality hardbound book nearby, pick it up and look at the top and bottom edges of the binding, near the spine, with the book closed. The little stripey tubes you see are called head and tail bands (one at the top, one at the bottom). They were originally invented to reinforce stitched binding, to prevent the cover from coming apart from the leaves. Today’s mass-produced hardcover books are glued rather than sewn, which makes head and tail bands purely ornamental. And yet for those who might notice, a book feels naked without such details.