Before coming to Italy I was not aware there are rules for pizza, but there are. In Italy,pizza must be cooked in a wood burning stove to qualify as pizza. Also
it must be cooked at a specific temperature before it is called
pizza. ( I believe this means that many of the bready-cheesy products
we find in the USA would not be called pizza should they find there
way to Italy).
The thickness of the crust is also regulated AND the amount of machine
involvement. For example you can not roll out the dough but need to
toss it in the air by a handsome strapping man with bulging muscles
(this may or may not be true but it really does help the digestion if
you BELIEVE it was made by a hunk).