Writing surface is a term used to describe the surface on which writing is done. The most common writing surfaces are SLATE, PAPER, DESK and BLACKBOARD. SLATE is a fine-grained metamorphic rock that is often used as a writing surface due to its smoothness and durability. PAPER is a thin material made from cellulose pulp derived from wood, rags or grasses, and is commonly used for writing and printing. Desks are pieces of furniture with a flat surface used for writing, reading and other activities. Blackboards are large, flat surfaces made of dark material, usually SLATE, chalkboard or porcelain, used for writing and drawing with chalk.