What is the passage mainly about? [originaltext] So you thought the hamburger

So you thought the hamburger was the world’s most popular fast food? But no, there is another truly universal fast food, the best fast food. It’s easy to make, easy to serve, and it’s delivered to your front door or served in fancy restaurants. It is the pizza.
    It’s kind of silly to talk about the moment when pizza was "invented". It gradually developed over the years. The idea of using pieces of flat, round bread as plates came from the Greeks. They called them "plakuntos" and ate them with various simple toppings such as oil, garlic, onions and herbs. The Romans enjoyed eating something similar and called it "picea". By about 1000 A. D. in the Italian city of Naples, "picea" had become "pizza" and people were experimenting with more toppings: cheese, ham and finally the tomato. Naples became the pizza capital of the world.
    Pizza migrated to America with the Italians at the end of the nineteenth century. But the popularity of pizza really exploded when American soldiers returned from Italy after World War II and talked excitedly about "that great Italian dish". Americans are now the greatest producers and consumers of pizza in the world.