Parchment is a thin material made from calfskin, sheepskin or goatskin, 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.
Parchment was developed in Pergamon, from which name it is believed the word "parchment" evolved, under the patronage of either Eumenes I, who ruled 263–241 BC; or Eumenes II, who ruled 197–158), as a substitute for papyrus, which was temporarily not being exported from Alexandria, its only source.
Herodotus mentions writing on skins as common in his time, the 5th century BC; and in his Histories (v.58) he states that the Ionians of Asia Minor had been accustomed to give the name of skins (diphtherai) to books; this word was adapted by Hellenized Jews to describe scrolls. Parchment, however, derives its name from Pergamon, the city where it was perfected (via the Latin pergamenum and the French parchemin). In the 2nd century BC a great library was set up in Pergamon that rivalled the famous Library of Alexandria. As prices rose for papyrus and the reed used for making it was over-harvested towards local extinction in the two nomes of the Nile delta that produced it, Pergamon adapted by increasing use of parchment.