Considered a peasant's meal in Italy for centuries, modern pizza is attributed to baker Raffaele Esposito of Napoli (Naples) in the Italian region of Campania, who in 1889 created a pizza especially for the visit of Italian King Umberto and Queen Margherita. The pizza, named Pizza Margherita after the queen, was very patriotic and resembled the Italian flag with its colors of red (tomatoes), white (mozzarella cheese), and green (basil). Pizza Margherita got rave reviews and set the standard by which today's pizza evolved. The idea of using bread as a plate came from the Greeks, who ate flat round bread (plankuntos) baked with an assortment of toppings. The tomato came to Italy from Mexico and Peru through Spain in the 16th century as an ornamental plant first thought to be poisonous. True mozzarella cheese is made from the milk of the water buffalo imported from India to Campagna in the 7th century. So the Neopolitan baker, as the saying goes, put it all together at the Pietro il Pizzaiolo pizzeria. Also, in 1830 the world's first true pizzeria, Antica Pizzeria Port 'Alba in Naples, opened and is still in business today!
Pizza migrated to America with the Italians. The first U.S. pizzeria opened in 1905 in New York City, but it wasn't until after World War II when returning GI's created a nationwide demand for the pizza they had eaten and loved in Italy that pizza went public. My first recollection of pizza is homemade "box" pizza (Chef Boyardee) with canned pizza sauce, hamburger meat, and parmesan cheese. In the late 1950's, Shakey's and various other mass production pizza parlors appeared and further popularized pizza.
Pizza in this day and age is not limited to the flat round type. It's also deep-dish pizza, stuffed pizza, pizza pockets, pizza turnovers, rolled pizza, pizza-on-a-stick, etc., all with combinations of sauce and toppings limited only by one's inventiveness. However, the best pizza still comes from the individual pizzaiolo, a pizza baker, who prepares his yeast dough and ingredients daily and heats his oven for hours before baking the first pizza.
* piz' za, n. (It.) - A baked pie of Italian origin consisting of a shallow bread-like crust covered with seasoned tomato sauce, cheese, and often other toppings, such as sausage or olives.