We worked our way through pounds and pounds of mozzarella for this issue, including authentic mozzarella di bufala from Italy; the milky, creamy fior di latte praised by pizzaioli in Naples; and cows' milk mozzarellas made in the U.S. Some were sturdy and smoky; others ethereal globes in saltwater brine. All brought wonderful textures and flavors to our pizzas. Here are 12 of our favorites.