Essential to Italian cuisine, olives and olive oil (olio di oliva) have been grown in Italy since the cows came home, or at least since the ancient Greeks colonised Sicily and the south.
Many extra virgin (top quality, very first pressed) olive oils are blends; those from Tuscany and Umbria are often a mix of Leccino, Frantoio and Pendolino, while some (usually very pricey) oils come from only one variety. In the 1980s, fancy restaurants started featuring olive oil sommeliers; today they are ranked and given points like wines.
An olio verde or olio novello is made from green olives, picked early (and supposedly very good for you). Occasionally you'll see an oil labelled denocciolato (pits removed before pressing).
Some of the main types of table and oil olives grown in Italy:
Baresane: light green cocktail olives from Puglia.
Bella di Cerignola (or della Daunia): mild, buttery green or black, or even distinctive red table olive from Puglia (DOP). Known as a 'beginner's olive' for anyone not used to the taste.
Biancolilla: very delicate oil olives, from Sicily.
Bosana: one of two native Sardinian varietals, used for oil.
Castelvetrano: green meaty table olive grown in western Sicily, also used for oil.
Cerasuola: also from western Sicily, producing an oil with a strong 'green' flavour.
Dritta: a mild, fruity oil olive (Abruzzo).
Frantoio: one of the main Tuscan culitvars.
Gaeta: black table olive from Lazio, used in salads, pizzas, sauces, etc.
Gentile di Larino: oil olive grown in Molise.
Itrana: grown in Lazio for a very green, herbal oil.
Leccino: another main cultivar grown for oil in Tuscany.
Moresca: olive producing a full bodied, sweet and fruity oil.
Mosto: produces a green oil, good for cooking (Puglia).
Moraiolo: Tuscan (and Umbrian) oil varietal.
Nocellara del Belice: same as Castelvetrano, above.
Nostrana di Brisighella: DOP monocultivar grown for oil around the town of Brisighella, in eastern Emilia Romagna.
Ogliarola Bradano: olives that make a spicy oil, from Basilicata.
Oliva infornata di Ferrandina: blanched, salted and then baked Majatica olives made around Matera in Basilicata (Ark of Taste).
Oliva minuta*: an ancient and very hardy cultivar that grows on the slopes of the Nebrodi mountains south of Messina in Sicily. The olives are harvested by hand and make a delicate oil (Ark of Taste).
Oliva tenera ascolana*: the big green olive grown in the Marche, used to make olive all'ascolana*, stuffed with meat and cheese and then fried in breadcrumbs.
Pendolino: classic oil olive from Tuscany.
Pisciottana: grows around Pisciotta in Campania (and nowhere else), the biggest of all olive trees, standing up to 15m.
Razzo: Tuscan oil olive cultivar.
San Remo: sweet nutty olive from Liguria.
Seggianese: DOP Tuscan oil, very fruity, often organically grown.
Semidana: Sardinia's other native cultivar, used for oil.
Taggiasca*: little black olives from Liguria, a favourite both for its fruity oil and for cooking.
Tonda Iblea: Eastern Sicilian oil olive, producing a green-golden oil.