Book jacket blurbs, also known as dust jackets or dust wrappers, are short summaries of a book's contents that are printed on the outside of the book's cover. They are usually written by the author or publisher and are intended to give potential readers an idea of what the book is about. Bios, which is the four letter answer to this crossword puzzle, is a shortened form of the word biography, which is a detailed account of a person's life.