Bookbinding - A style of spine construction where the spine of the book block is attached to a paper tube, which is then glued to the covering material.

  _____________     _____________  \
  ____________ \   / ____________   > <- pages
  ___________ \ | | / ___________  /
             \/     \/
 ============/       \============ <- cover

            Hollow back
           moves down as
            book opens

The hollow back style was invented in France in the late Eighteenth century, and spread to the rest of the bookbinding world in the early Nineteenth. Along with French grooves, it makes for books that are much easier to open than the older flexible binding style.

For bookbinders, however, the advantage to a hollow back is that it is much easier to construct than a flexible binding. Their invention made it possible for less skilled binders to create attractive books at lower cost. It also opened the way to cased in bindings and the mechanisation of bookbinding.

T.J. Cobden-Sanderson, and other binders of the Arts and Crafts movement, blamed the hollow back for the rise of mass-produced books. They led a return to the older flexible binding style as a way of displaying the bookbinder's craftsmanship. Even now, fine binders only use hollow backs when binding very thick volumes. Mass-market printers, by contrast never use anything else on hardcover editions.