What makes a pizza pie Neapolitan depends on where you are and who you ask.
In Naples, pizzas are individual affairs, about 12 inches in diameter, and baked in a dome-shaped, wood-burning oven, un forno a legna.
The true Neapolitan pie is bordered by a thick but puffy rim, cornizone in Italian, and the crust itself is floppy enough for the point to be folded back toward the rim for consumption. In fact, Americans who visit Naples invariably complain that the pizza is too soft, underbaked. For this reason, many Neapolitan-style pizzerias in the United States try to strike a balance between authenticity and crispness.
Neapolitan vs. Sicilian vs. Grandma
Here's where things get confusing. In the New York area, the two standard styles of pizza are called Neapolitan and Sicilian. The former is big, round and relatively thin; the latter is big, square and relatively thick. Both are pretty well covered with tomato sauce and shredded, industrial mozzarella, and neither has much to do, historically, with the region of Italy for which it is named.
Another familiar specimen on Long Island is grandma pizza, which is baked in the same rectangular pan as Sicilian but has a thinner crust and is topped sparingly with crushed canned tomatoes, shredded mozzarella, chopped garlic and oil. All three of these Italian-American pies are made in a gas-fired deck oven, the most common pizza oven in the United States, but they are derived from earlier pies baked in ovens fired by coal.
From wood to coal to gas
The Southern Italians who immigrated in the late 19th century brought with them their wood-burning pizza tradition, but in New York they found that the cheapest and most plentiful fuel was coal, which burns a good 300 degrees hotter than wood. The intense heat of the coal oven transformed Neapolitan-style pizza, with its soft, breadlike crust and lightly cooked toppings, into the classic New York pie: crisp and slightly charred, with the tomato and cheese clinging to the thin crust in a molten matrix. As technology changed, many bakeries and pizzerias converted their coal-burning ovens to gas-burning ones, which are far easier to operate and maintain.
The great old-school pizzerias of New York (Lombardi's -- established in 1897 -- John's, Arturo's, Totonno's, Patsy's) and their Long Island progeny (Salvatore's, Grimaldi's, Massa's) still make these supernal coal-oven pies.
In Manhattan and Brooklyn, pizzerias that identified themselves as authentically Neapolitan (Franny's, Roberta's, Motorino, Co., Keste, L'Asso) started opening around eight years ago -- and haven't stopped. On Long Island, the Neapolitan mantle was taken up by Pizzetteria Brunetti in Westhampton and Grana in Jamesport (both opened in 2010). They are now joined by Flip in Mineola and Red Tomato in East Norwich.