Dust jacket

The dust jacket of a book is "the detachable outer cover, usually made of paper and printed with text and illustrations," also called a book jacket, dust wrapper or dust cover. "This outer cover has folded flaps that hold it to the front and back book covers," and the flaps carry the sales copy: a blurb, the author's biography, or praise from notable figures, with the barcode and ISBN on the back. Jackets began as protection for ornate cloth bindings; the oldest surviving one, from 1829, enclosed the whole book and was "discarded like gift-wrapping paper," and by around 1920 the artwork and decoration had migrated from the binding to the jacket, which became the book's advertisement.

For the self-publisher the jacket is the hardcover's billboard: cover art, flap copy and back-panel praise all live on it, and flap copy is the craft taught in how to write a book blurb.