Interesting you should ask, since I don’t really know the answer. Or at least I don’t know the full extent of the answer, which is spelled out to last detail in a 42-page scholarly paper on the subject that resides in some Italian governmental filing cabinet. However I do know the gist of it.
First and foremost, D.O.C. pizza requires the use of all natural ingredients, ideally local to Naples. Among them San Marzano tomatoes, which are grown right nearby in the nutrient-rich soils around the base of Mt. Vesuvius. Notice there I said “tomatoes”, not “sauce” for real Neapolitan pizza does not have sauce on it, just crushed tomatoes, (and no, no salt). What no garlic? Nope, not allowed, that is unless you’re making a specific variety of Neapolitan pizza known as a pizza marinara. Then it’s OK. As far as other toppings are concerned, only buffalo milk mozzarella (and no that’s not a brand name, it’s mozzarella made from fresh buffalo milk), extra-virgin olive oil, fresh basil and dried oregano. Other meat and shellfish toppings are permitted, but no more than two, and they must be fresh and/or unprocessed.
As far as the dough is concerned, only Italian “00” flour may be used, preferably leavened with a natural starter grown from the locale around Naples. “Brewer’s” yeast is allowed though not encouraged. Salt is allowed in the dough, which should not (but may) be mixed by machine, but only on low speed. Finished dough must be stretched to shape by hand then baked in a wood (not coal, not gas, not electric) oven at no less than 900 degrees Fahrenheit for no more than 90 seconds (did I mention the wood has to be oak?). I’m not sure how you eat it, but my guess is that there are rules about that too.
To what extent do I/will I buy into all this? Not to any great degree since I live in America. But then there’s no sense in being a total reactionary either, since I am interested in producing the best possible Neapolitan pizza I can given the ingredients and equipment I have on hand. I’ll just have to see how it goes.