Parchment

Central European (Northern) type of finished parchment made of goatskin stretched on a wooden frame
Parchment with a quill and ink

Parchment is a writing material made from specially prepared untanned skins of animals—primarily sheep, calves, and goats. It has been used as a writing medium for over two millennia. Vellum is a finer quality parchment made from the skins of young animals such as lambs and young calves.

It may be called animal membrane by libraries and museums that wish to avoid distinguishing between parchment and the more-restricted term vellum (see below).