The term 'book cover' can refer to several different elements of a book. BINDING is the process of attaching the pages of a book together, usually with glue or thread. A JACKET is a protective cover made of paper or cloth that is placed over the BINDING of a book. A penname is a pseudonym used by an author when publishing their work. Finally, a dustjacket is a paper cover that is placed over the book's BINDING and JACKET, usually for protection and decoration.