Vellum is prepared animal skin or membrane, typically used as writing material. It is often distinguished from parchment, either by being made from calfskin, or simply by being of a higher quality. Vellum is prepared for writing and printing on single pages, scrolls, and codices (books).

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.