The material that the contents of a book are bound in; the covers. The name dates from the first days of printing, in the 15th and early 16th centuries, when wood (often, oak) was used for binding. The term “original boards” may be used especially to indicate the original paper-backed boards — intended as a temporary binding — that were used to case many books from about 1740 to roughly 1830, when cloth began to replace temporary covers. In addition to wood, materials that have been used for bookbinding boards include pasteboard, a hand-laminated material built from waste sheets of pasted paper; strawboard, a cheap, yellow, machine-made product based on straw; and modern machine-made paper pulp board.
The stiff material used for the covers of a book. The name is derived from the fact that the earliest bound books were literally bound between two pieces of wood, usually oak. The same expression continues today, although the "boards" are not wood but a thick cardboard. "In boards" means either in the uncovered boards or in boards which are covered with paper.