A board book is a type of book printed on thick paperboard. The paperboard is printed and used for both the cover and the interior pages. Each page panel is a minimum of two plies of paperboard thickness. Unlike a typical paper book that is bound with saddle stitching (staples) or perfect binding, a board book's pages are specially folded and bound together. Board books are very durable and consequently intended for small children, who often tend to be less gentle with books. Most of the board books produced in the world are produced in China and Mexico; however, there is one board book printer still located in the United States and one in Poland - Gryf Direct.