It is made from raw cow's milk, collected immediately after milking and partly skimmed by gravity.
Traditionally, cows have to be fed only on grass or hay. Only natural whey culture is (allegedly) allowed as a starter, together with calf rennet. The only additive allowed is salt. The product is aged an average of two years. The cheese is produced daily, and it can show a natural variability.
The name is trademarked, and in Italy there is a legal exclusive control exercised over its production and sales by the Parmigiano-Reggiano cheese Consorzio (created by a governmental decree).
See also: List of cheeses