Can anyone imagine a world without pizza?

The first real pizzeria is said to have been Antica Pizzeria Port'Alba which opened in Naples in 1830, although the company had been producing pizzas to be sold by street vendors for almost a century before this. Remarkably, it is still in business today.

Almost sixty years later, in 1889, Neapolitan baker, Raffaele Esposito, is believed to have created the first margherita pizza. Esposito devised what is probably the most popular (and certainly most basic) pizza of all, as a special treat for the visiting Queen of Italy and Savoia, Margherita (originally of Austria) and her husband Umberto I. Obviously trying to make an impression on the couple, he named this new dish after the queen, and used the colours of the Italian flag - red, white and green - to underline his patriotism. What's more it tasted good and this so-basic, yet universally loved pizza version was born.

Even today the tongue-twistingly named Associazione Verace Pizza Napoletana (Association of True Neapolitan Pizza) imposes strict guidelines on its worldwide members, dictating the type and amount of ingredients that may be used to create 'true' Neapolitan pizza. An authentic margherita, for instance, may only be topped with tomato, olive oil, grated parmesan, and fior-di-latte or mozzarella. Some bakers add a leaf or two of basil. According to the association's mandate, true Neapolitan pizzas must only be baked in a wood-fired oven (forno a legna), and each pizza base must be entirely shaped by hand.

The rules further state that "variations of pizzas are recognized if they are informed by the Neapolitan tradition of pizzas and are not in contrast with the rules of gastronomy", which brings into question the many variations now dreamed up around the world. Tandoori chicken pizza, anyone?

Basically a flat bread baked in an oven with something on top, pizza (the word means simply 'pie') was possibly baked for many centuries before it went commercial. It was originally peasant food, simple to cook, tasty, and similar to breads cooked in many other countries. Only Italy managed to turn the concept into an art-form - and an international industry. With widespread Italian migration in the 20th-century, it wasn't long until the whole world knew about - and loved - pizza.

In Italy, pizza may be sold in the familiar round shape or brought steaming from the oven in massive lengths and sliced into rectangular pieces and sold by the piece al taglio. Calzone, is really a folded pizza with the 'topping' now becoming the filling, enclosed inside a bread pie. Interestingly, when eating casually, Italians often fold their slices of flat pizza in half anyway, for convenience.

Toppings vary, but there are favourites such as the margherita, of course, which can be infinitely varied from its basic base with prosciutto crudo (raw) or cotto (cooked), capricciosa with sausage, prosciutto, or olives - in fact anything according to the 'whim' of the chef, for that is what the word means.

Toppings vary from the unusual but delectable potato and rosemary, to seafood pizzas, mushroom and cheese, and others topped with salami and regional specialties

Napoletana is very simple, just oregano, tomato and olive oil, while Rome's answer, the romana, adds anchovies and mozzarella to this. Pizza pugliese involves tomato, mozzarella and onions, and pizza siciliana mixes tomato, mozzarella, capers, olives and anchovies. Southern pizzas almost certainly will have options that include chilli.

But don't be fooled by marinara which is simply tomato, garlic and oil - and contains no seafood. This topping was the one favoured by fishermen, because they wanted a pizza to eat with their fish. It has no cheese, something that Italians are adamant should never be placed on a plate with seafood.

For those who can't decide, there's always the four seasons pizza, quattro stagione, in which each quarter of the pizza is topped differently, or quattro formaggi, which uses four types of cheese .

Pizza dough is simply bread dough made with doppio 00 white flour. The dough is allowed to rise then often shaped theatrically by the pizzaiolo, the pizza maker, as he flings the dough into the air, turning and stretching it each time, until it reaches the size and shape he desires.

Italian pizza bases are much thinner than their overseas cousins, although roughly the same diameter. In Italy, they often have just a crisp cracker base with a smear of topping, and are cooked in just a few minutes in the furnace heat of the wood-fired oven which is the heart of every pizzeria. One pizza is not large enough to share, and it is possible for one hungry person to eat a couple.

What a journey pizza has had - evolving from peasant ovens and street food to the world-s favourite snack.