the.com/dust jacket

means The removable printed paper wrapper that covers a hardcover book's binding, carrying the title, art, and blurbs.

from From 'dust' plus 'jacket' (a coat), first paired this way in the 1800s when publishers began slipping paper wrappers over cloth bindings — originally plain, purely protective wrapping meant to shield the cover from grime and shelf wear during shipping and storage. Only later did booksellers realize the wrapper could sell the book, and it became the illustrated, blurb-covered billboard we know now; the plain protective sleeve underneath got dressed up into the main attraction.