Vellum is derived from the Latin word “vitulinum” meaning "made from calf", leading to Old French “Vélin” ("calfskin"). It is mammal skin prepared for writing or printing on, to produce single pages, scrolls, codices or books. It is a near-synonym of the word parchment, but "vellum" tends to be the term used for finer-quality parchment.
Vellum is generally smooth and durable, although there are great variations depending on preparation, the quality of the skin and the type of animal used. The manufacture involves the cleaning, bleaching, stretching on a frame (a “herse”), and scraping of the skin with a hemispherical knife (a “lunarium” or “lunellum”). To create tension, scraping is alternated with wetting and drying. A final finish may be achieved by abrading the surface with pumice, and treating with a preparation of lime or chalk to make it accept writing or printing ink. Modern "paper vellum" (vegetable vellum) is used for a variety of purposes, especially for plans, technical drawings, and blueprints.
Read more about Vellum: Manufacture, Paper Vellum, Preservation