Here are some ingredients I like to always have on hand for cooking Italian food:

A good, general purpose extra-virgin olive oil, for cooking and making vinaigrettes. The brand I use is Colavita; it tastes good and is not very expensive (about $15 for a liter).

A high-quality, estate-bottled olive oil, for finishing pastas, salads, soups, and fish and meat entrees. There are many different olive oils available in Italian and specialty food stores, and each has its own characteristics. Some are light, delicate, and fruity, while others are more full-bodied and peppery. Tuscan and Sicilian oils tend to be of the fruitier type, while those from Puglia tend to be spicier. The different flavors come from the variety of olive used, as well as the point of ripeness when they’re harvested; Tuscan olives are picked when still unripe, while Pugliese olives are fully matured when picked.

An estate oil will run around $20-$25 for a 500-750 mL bottle. (Smaller bottles are sometimes available.) That may seem like a high price point, but considering the difference a great oil can make in a dish, and the fact that the serving size is just one tablespoon (15 mL) or less, an estate olive oil can be a great investment in one’s cooking.

White and red wine vinegars, used for many purposes in Italian cooking, from making vinaigrettes, to pickling vegetables, to drizzle over meats to cut the fat, and in the South, along with sugar, to achieve the characteristic sweet-sour taste known as agro-dolce.

Balsamic vinegar from Modena. Make sure that you buy a real balsamic vinegar, and not an imitation. There are many low-quality fake Balsamic vinegars on the market. One way to spot a fake is to check the ingredients: caramel is added to many cheap Balsamic vinegars to sweeten it and give it a dark color. There is also traditional Balsamic vinegar, which is a protected product make by a specific procedure, and can be aged for up to 50 years. Traditional Balsamic vinegars are an investment – they can be extremely expensive, depending partly on how long they’ve been aged, but just a few drops will add a significant amount of flavor to a dish.

Parmigiano-Reggiano cheese, which is completely different from Parmesan cheese. Parmesan is the English name for the Italian hard cheese used around the world to season and flavor all types of dishes, and to finish pastas. However, “Parmesan” cheese can be produced by any type of process (think Kraft grated Parmesan), and can have any type of flavor (or barely any flavor at all). Parmigiano-Reggiano, then, is an Italian name derived from two of the areas in the Emilia-Romagna region where it is produced, Parma and Reggio Emilia. The name Parmigiano-Reggiano is protected by DOP (Denominazione di Origine Protetta, or Protected Designation of Origin) status, enforced by the European Union, and any cheese labeled as Parmigiano-Reggiano must have been produced in either of four areas in Emilia-Romagna, or one area in Lombardy. True Parmigiano is made by a specific procedure, aged for up to two years, and has a flavor far greater than anything sold under the name Parmesan – taste for yourself, and you will see.

Pecorino cheese, my other favorite Italian cheese for cooking. Unlike Parmigiano-Reggiano, there are several different varieties of Pecorino produced in several regions of Italy. The most common is Pecorino Romano. Pecorino is a salty cheese, while Parmigiano is also salty, but a little sweet as well.

Pancetta and prosciutto di Parma, two of the many Italian cured pork products, are great to have in the fridge. They add great flavor to sauteed vegetables, pasta sauces, soups, braised meats, or any number of other dishes. Pancetta is unsmoked bacon, and prosciutto di Parma is the cured hind leg of the pig. Like Parmigiano-Reggiano, prosciutto di Parma is protected by DOP status, and can only be produced in Parma, in the Emilia-Romagna region. The leg is first cured for a few days, then hung to dry for a period of up to two years. This lengthy process accounts for the high price of Prosciutto; a whole leg of Prosciutto costs about $150, while sliced Prosciutto is usually sold for about $25/pound. Although expensive, Prosciutto has a unique and extraordinary flavor, and being cured, will last quite a long time under refrigeration. My favorite Italian store, Buon Italia in New York, sells scrap hunks of prosciutto from the bottom end, where it gets narrow and harder to slice, as well as overcured. I bought one of these and keep it in the refrigerator, cutting a few slices now and then to eat as is or to dice or cut into thin julienne and use in a pasta sauce.

Imported Italian plum tomatoes, usually sold canned but sometimes in waxy boxes. The best are the San Marzano variety, another DOP product grown in a town near Naples in the Campania region. Compared to the more common Roma variety, San Marzano tomatoes have thicker flesh, fewer seeds, and a stronger, sweeter, less acidic taste – all qualities which make them excellent for pasta sauces. My favorite brand of plum tomatoes, both San Marzano and regular, is La Valle. The San Marzano tomatoes are a little more expensive, but worth the extra cost when the tomatoes play the main role, such as in tomato sauce.

Chile flakes are the easiest way to add some heat to a dish, and if you’ll be cooking Southern Italian, you’ll definitely be using chile peppers in some form. Although I prefer fresh chiles, I don’t always have them on hand; nothing beats the convenience of the flakes.

Capers are another important Southern ingredient. The best capers are sold packed in salt. They have a pungent flavor that combines so well with garlic, anchovies, and olives, and they are great for flavoring seafood, vegetables, pasta sauces, and other dishes.

Salted anchovies are a classic Italian seasoning. They add a salty fish essence that gives flavor to so many different dishes. Like capers, a can of salted anchovies will last indefinitely in the fridge, so you can use a few at a time and always have them on hand.

Black and green olives are among my favorite things to cook with, and they play an important role in the cuisines of so many Italian regions. There are countless varieties of olives, and each has their own characteristic and nuances of flavor – some are bolder, some are milder, some are fruitier, some are more bitter.

Red and white wine are of course invaluable in the Italian kitchen. I try to always have at least one bottle of each type in the kitchen. I’m by no means a connoisseur, but I do like to try different varieties of wine, both for cooking and drinking.

Homemade chicken stock is the single most important item I keep in my freezer. It’s an indispensable source of flavor for soups, sauces, braised dishes, and many other preparations. I make a large batch from several pounds of cheap chicken parts – backs, necks, feet, etc – which are practically free at the few grocery stores that sell them. (Look around at a few stores, and search on chowhound.com to see if there are any sources in your area.)

Sea salt has a very nice flavor and a sprinkle of it is great for finishing dishes. I like coarse sea salt, as it also provides a textural contrast to a dish.

My favorite place to buy Italian ingredients is Buon Italia, in Chelsea Market in New York. They have an enormous selection of high-quality Italian products, and they also have an online store.