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.