Book rebinding is the renewal or replacement of the cover of a book. Typically, this requires restitching or renewal of the glue which holds the pages in place.
Collectors of antique books such as incunabula would often have them rebound. This might be done to improve their appearance by rebinding in a more fashionable colour or to assert ownership by having the book rebound in uniform covers which were stamped with an insignia such as a coat of arms. One prominent collector who had this done was Earl Spencer. For example, when he acquired a medieval psalter of 1457, which was bound in pigskin on wooden boards, he had it rebound in mauve velvet over cardboard. The Bodelian Library rebound additions to its collection for functional reasons -- to indicate value and importance. The Bibliothèque nationale de France requested 6600 francs for bookbinding in the eighth year of the revolutionary calendar, "those which come from our conquests in Germany and Italy, and while infinitely precious, they have arrived to us in a deplorable state".
The four-volume copy of Audubon's Birds of America held in the Royal Collection was rebound in 2011 by conservators at Windsor Castle. The volumes are especially large and heavy, being printed on double elephant paper of about 50 by 28 inches, and weighing over 50 pounds. The plates, which were published loose, had been originally bound by the royal bookbinder, James Mackenzie, around 1840. That leather cover had perished and the tight sewing of the pages made viewing difficult as the pages might tear. The rebinding was done in nine stages: