Round, from soft dough, with high crust (frame). Classic Neapolitan dough does not permit any kind of fat, only water, flour, yeast, salt.
Round, from very thin and crispy dough. The dough is made from "00" or "0" Italian flour, water, yeast, olive oil or seed oil and salt so that the dough turns out to be hard and consistently.
Pizza is popular all over the world. The largest consumers per capita are: Canadian, Australian and of course Italian. It spread significantly also because of large international fast food chains.