A book with French flaps indicates a trade paperback with long covers which are folded inwards. This gives the book a more expensive look, creating the half assed illusion of a hardback. The flaps make the front of the cover seem thicker, although not as thick as a standard hardcover book, and additional information can be printed on them, such as the plot synopsis, blurbs and the author's picture and/or biography.

A french flap envelope is a tall rectangular envelope (the top and bottom being the narrow sides) with a long, pointed flap at the top.