The term Board, may refer either to a piece of lumber or to a hard sheet of some other material, such as cardboard, Masonite, etc. In US, it refers to paper thicker than one hundredth of an inch. The term Board may also refer to a billboard. Some types of board are: Bristol board, Duplex board, Cloth centered board, Mill board, Chip board, Grey board, Ivory board, Paste board, and Straw board, etc. In context of art, the term Board may also refer to a theatre stage.