Parmigiano Reggiano is a DOP (Denominazione di Origine Protetta) cheese, which means its production is guaranteed by Italian law.
At about 12 months old, the minimum allowed by Italian law, this medium-fat semi-hard to hard cheese is pale colored, noticeably but not overly salty, with a little sharp acidity, and a mildly nutty nose. It is never pungent or stinky. The aroma is sweet & fruity; the taste is intense, salty, sweet & may vary from fruity to caramelized onions.
Have you noted differences with the Parmesan or Reggianito? Because Parmigiano Reggiano d.o.p. is the real thing, whereas the others are imposters: Parmesan, Black Wax Parmesan, Reggianito,… It’s not mere snobbery that should guide your buying, but flavor and tradition. The «fake cheese» have little of the burst of complex flavor that Parmigiano Reggiano d.o.p. has; they are mostly salty, often acidic, and lack character, requiring far more cheese to register on your tastebuds. Parmigiano Reggiano d.o.p. costs more per kilogram, but you and your client will use less of it to get more flavor than the ersatz “parmesans”.