Refers to the edges of the cover of a book bound in paper or another soft material. These yapped edges are not flush with the pages but extend beyond the edges of the book and are fragile by nature.
CJ grew up admiring books. His family owned a small bookstore throughout his early childhood, and he would spend weekends flipping through book after book, always sure to read the ones that looked the most interesting. Not much has changed since then, except now some of those interesting books he picks off the shelf were designed by his company!