Little is known about authentic Italian food until you actually get to Italy and you are reading an Italian menu. Where are the spaghetti with meatballs? Fettucine Alfredo? You will find none of that in Italy: those are in fact Italian American dishes.
Northern, Central and Southern Italian cuisines are actually very different from each other - in the North, you'll find dishes that include different types of meat such as veal, rabbit, game (deer), horse steak (called "cavallo" or "puledro"), along with the ordinary chicken, turkey, beef, and duck. In Italy you can eat all parts of the animals: the typical liver with onions (fegato alla veneziana) done in Venice, the tongue in green sauce (lingua al bagnetto) served in Piedmont, the guts with beans (trippa) that can be found in Tuscany together with the delicious pate of hearts and livers on bread, the spleen burger with lemon in Palermo (pani ca' meuza) and the you-do-not-want-to-know-what-it-is "paiata" that can be tasted only by the brave in Rome. Salads are usually served as a side dish (not as an appetizer) and fruit can be served as dessert, along desserts at the end of the meal; there is no such thing as frosting in Italy, but a more delicate whipped cream.
In Southern Italy, food is richer in spices and changes flavor a little bit: you will find pasta everywhere - however, in Northern Italy risotto is more widespread than pasta, whose shapes may be called in a different way depending in which part of the country you're in. However, spaghetti seems to be the universal word while ziti is not!
Don't leave Italy without trying their delicious ice cream: it looks like a soft serve ice cream, only creamier and in different flavors! Pizza is an absolute must! If you have dinner at a pizzeria your pizza will be served to your table on individual dishes, that's why you need to pick your own pizza and then (maybe) share it, if you are in company. They won't slice it for you so you'd better ask for a good knife or fold it over as if you were eating a calzone. Italians usually do not eat pizza with hands, but it can be done if you like to.
If you order coffee (caffè) at a restaurant or at a bar, their "regular" coffee is an espresso, so make sure you order a caffè americano if it is indeed the regular American coffee you mean to ask for. There is no cream in bars and restaurants in Italy, so your only alternative to a black coffee is milk (latte, not to be confused with the homonymous beverage they serve at Starbuck's). There are many kind of coffee drinks: macchiato (literally "spotted", it's espresso + a drop of milk), corretto (literaly "adjusted", it's espresso + liqueur), cappuccino, lungo, ristretto, marocchino... Beware when they will ask you if you like it steamed or cold! Caldo (hot)? Or freddo (cold)?
There are some other differences between Italian American cuisine and real Italian one. Cappuccino can be found only at breakfast, since in Italy breakfast consists mainly of sweet food. You will not find a cappuccino in a restaurant and they will not serve you eggs and bacon in a bar for breakfast. There is no cream in the carbonara, since the original recipe includes only eggs, guanciale (the cheek of the pig), pecorino cheese and black pepper. "Pepperoni" isn't an Italian word, if you ask for peperoni (with no doubles) you will receive peppers, so don't order a "pepperoni pizza" unless you mean a pizza with peppers. Pizza usually has thin crust in the North and thick crust in the South, but you can find some original Southern pizza even in Northern Italy. Pasta can never be a side dish. It's a "primo". In Italy the meal is composed of Antipasti (appetizers), Primo (ONLY pasta, rice or soup), Secondo (main dish), Contorno (side dish), dessert, coffee and "ammazzacaffè" (literally "coffee killer") that is a small shot of highly alcoholic drink. Since chicken and meat can only be a secondo, you will not find any pasta or rice with chicken or meat, the only exceptions are Ragù (the so-called "bolognese sauce" abroad) and tortellini, in Bologna traditionally served stuffed with a mixture of chicken and beef.
Italian cuisine is strongly, proudly and deeply regional: so, moving from a city to another, means changing it completely, at the point that cuisine from other parts of Italy is considered "ethnic food" with dedicated restaurants.
