D.A.'s logo on a piece of parchment
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 with changes in relative humidity and is not waterproof. The finer qualities of parchment are called vellum.
Even in modern times, parchment has been called the "finest writing material ever devised". Modern products do not reach the quality of medieval manufactured parchment.
In the wizarding world, parchments take the role of normal paper, and all wizards and witches use them as writing material, along with quills and ink. Dolores Umbridge has pink-colored parchments.