Once upon a time a books were cherished, kept forever and day, and catalogued at home with beautiful printed bookplates (or ex libris) printed with the owner’s name and a fanciful image of some sort which were pasted to the interior front cover so you reclaim your book in the event it was lent out to someone.
It’s kind of a shame that they aren’t used much anymore but you can see samples the bygone era of bookplates online in the University of Connecticut Ercolini Bookplate Collection.