Parchment

Parchment is a thin material made from hide; often calfskin, sheepskin or goatskin, and often split. Its most common use was as a material for writing on, for documents, notes, or the pages of a book, codex or manuscript. It is distinct from leather in that parchment is limed but not tanned; therefore, it is very reactive to changes in relative humidity and is not waterproof. Finer-quality parchment is called vellum.