Parmesan or Parmigiano Reggiano, is the noblest of a group of Italian cheese, called formaggi di grana, or hard cheeses with a grainy texture. Parmesan comes as a wheel-shaped, golden-coloured cheese. Parmesan is made by finely cut, carefully separated curd, which is then stirred and scalded to 58oC (137oF), which is then pressed. These formaggi di grana are then salted over a period of weeks, after which they are left to mature for 2-3 years, or longer. Parmesan is then categorised as: vecchio (old); stravecchio (extra old); tipico (4-5 years old); and giovane (less mature, table cheese).
Other formaggi di grana include: Grano Padano made throughout Lombardy; Grana Lodigliano, a low fat cheese with an "eyed" paste of small holes; and Grana Lombardo from around Milan.
Dowell, P., Bailey, A. (1980) The Book of Ingredients, Dorling Kindersley. ISBN 0718119150.