Parchment is a thin material mae from calfskin, sheepskin or goatskin. Its most common use is as the pages of a book, codex or manuscript. It is distinct from leather in that parchment is not tanned, but stretched, scraped, and dried under tension, creating a stiff white, yellowish or translucent animal skin. The finer qualities of parchment are called vellum. It is very reactive with changes in relative humidity and is not waterproof.