Parmigiano Reggiano cheese is a hard, dry cheese made in Italy. In fact, the name is trademarked and only cheese from a certain region - mostly around the areas of Parma, Reggio Emilia, Modena, Bologna and Mantua in Italy - can officially be called Parmigiano Reggiano. Similar cheeses made outside this area are called simply parmesan cheese. The cheese has been produced in the same way for the past 800 years. The Consorzio del Formagio Parmigiano Reggiano has published a "multimedia journey" on their website that takes you through the steps of making this cheese. To summarize the process, however, a blend of whole and part skim milk is cooked in huge copper kettles, to which a cultured whey starter is added. This starter contains the precise bacteria needed to start the development of the cheese and is refreshed every day from the prior day's cheese making. Rennet, a thickening enzyme, is added and the cheese mixture is heated gently to expel water from the curds. The partially dry cheese is molded, salted and finally set to age. Parmigiano Reggiano should age for over 24 months to develop optimum flavor and texture, though the minimum aging is 12 months.

The US standard for parmesan cheese is that it must be aged for at least 10 months. In Italy, they cure the cheese for at least a year before selling it as Parmigiano Reggiano. In fact, only cheese from strictly regulated dairies in Parma, Italy can be called Parmigiano Reggiano; other cheeses must only be called parmesan. Kraft Foods is petitioning the FDA to reduce the aging standard for US parmesan to a mere 6 months, saying that their consumer taste tests show acceptance for the new product, which can be produced more cheaply and in greater quantities than the current product.

Italians, as well as other cheese producers in the US, say that the long aging is what allows the distinctive crumbly texture and delicious flavor to develop. It is possible that the World Trade Organization would consider restricting the use of the word "parmesan" by setting a minimum aging standard, if the US standard is changed and if there is enough international protest. A restriction on the use of the "parmesan" name would adversely affect US exports of the cheese.