The Italian sauce made from basil, pine nuts, Parmesan, and olive oil is pesto.
More precisely, the classic version is pesto alla Genovese, associated with Genoa in the Liguria region of northwestern Italy. Its traditional ingredients include Genovese basil, extra-virgin olive oil, pine nuts, garlic, and hard cheeses such as Parmesan, often combined with pecorino. The ingredients were traditionally crushed together in a marble mortar with a wooden pestle, which explains the name: pesto comes from the Genoese verb pestâ, meaning “to pound” or “to crush.”
Pesto is commonly tossed with pasta, spread on bread, or used with vegetables, potatoes, and soups. It is not the same as béchamel, a milk-based white sauce; Alfredo, a butter-and-cheese pasta sauce; or marinara, a tomato-based sauce.
The modern basil-based preparation emerged in nineteenth-century Genoa, although earlier Mediterranean sauces used crushed herbs, garlic, cheese, oil, and nuts. Today, “pesto” can describe many pounded sauces, including Sicilian versions made with tomatoes and almonds. Without a regional qualifier, however, pesto usually means the green Genoese style.