Ever wondered what those coloured pieces of thread at the top and bottom of a hardback book spine were called? Have you even noticed them? Wonder no more! These are the head and tail bands - usually shortened to H&T bands.

Head and tail bands have been used in book binding in one format or another since the twelfth century, although they didn't appear in their current form until around the sixteenth century. Originally they were sewn into the book and used to reinforce the binding. They made the spine stronger so when the book was repeatedly pulled off bookshelves, the case did not come away from the book block. These days they are glued in during the automated binding process, rather than sewn in, and serve a purely decorative purpose. H&T bands are only used on hardback books, and the spine needs to be around 8mm for H&T bands to be added.

The Book: Its History and Development, by Cyril Daven port (1907)

While they may go unnoticed by those outside the industry, they provide the final finshing touches to a book's design, and are usually chosen with care to match a prominent colour on the cover, and are available in a huge array of hues.