On another thread there was a detour as some folk discussed pizza toppings. Got me to thinking--exactly what is pizza? Is it merely a flatbread with whatever toppings you choose to throw on it? Or is it a traditional red-sauce, mozzarella, and some meat or veggie toppings? I'm not looking for a best-of kind of discussion; nor a comparison of, say NY pizza to deep dish (we all know that whatever deep dish is, it is not pizza). But the simple fact is, Canadian bacon and pineapple is a long, long way from the pizza I grew up on. So, really, what, exactly, is pizza?