Nocino is a sticky dark brown liqueur from the Emilia-Romagna region in Northern Italy. It is made from unripe green walnuts. To make a truly authentic Nocino, one must use the most widely known walnut variety, the Juglans regia. The walnuts and the liquor have to be cut / handled using ceramic or wooden tools (in order to avoid oxidation) and placed in an alcoholic base. After steeping in spirit, the walnuts are removed and the now-black alcohol is mixed with simple syrup. Nocino has an aromatic, but bittersweet, flavor. It may be homemade; villages and even individual families often have their own (oftentimes secret) recipes, including different additions like cinnamon, juniper berries, lemon or orange zest, vanilla pods, coffee beans or clove. The classic base consists of Vodka. Nocino is also available commercially in bottled form. Commercially available Nocino is typically 40% alcohol by volume, or 80 proof.
According to Roman historians, the nocino actually was born in Britain. The earliest records are related to the Picts (from the Latin picti, meaning painted) so called by the Romans because they used to paint their skin in blue. The Romans also recorded the strange traditions of these people on June 24, when they drank a very special brew, and they said they could talk with goblins, with elves and Goddesses. When the Romans made Christianity the official religion of the Empire (in 313 AD), these ancient rites, in order to survive, had to be "translated" into the tradition of the Bible. Thus, they became associated to St. John the Baptist, who, according to the tradition, was born on the Summer Solstice. 
Nicholas Culpeper wrote, “The young green nuts taken before they be half ripe and preserved with sugar, are of good use for those who have weak stomachs.” He also mentions that ounce or two of a distillation of the same age of husk, is used to “cool the heat of agues and resist the infection of the plague.” 
This drink or potion made its way to Celtic France and to this day, a similar drink called liqueur or Brou De Noix is made in many French regions. At some point, this practice of infusing green walnuts came to the Italian peninsula where it became known as Nocino or, in the case of Piedmont, Ratafià Di Noci (walnut ratafià).
Ordine del Nocino Modenese is an association of Spilamberto, Province of Modena, Emilia-Romagna, Italy which, since 1978, promotes the traditional Nocino of Modena. In an interview they describe an ancient custom: "Witches were very fond of nuts, therefore on June 24, this very important date, they came out of the trees and wanted to steal the walnuts. And then the farmer, who did not want walnuts to be stolen, because he had to make Nocino, he made this big bonfire, this big fire, next to the walnut tree, and it was also a way of getting together - for the whole neighborhood.". In the same interview, they reveal a local legend: the reason for which the Nocino is made in the night between the 23rd and 24th of June is that, since it is an important Paganism as well as Christian\Christianity date, the walnuts "are impregnated with a dew that is the panacea for all diseases!"
According to tradition, the very best Italian Nocino requires barefoot virgins gathering an uneven number (21 or 23) of soft, green, dew-laden walnuts which they would leave to dry by the remains of the threshing fires that had been used to quicken the process of separating the wheat. Tradition also dictates that the walnuts have to be and harvested by hand, one at a time, so as not to damage the shell, during the “night of San Giovanni” or St John the Baptist Day (24 June). The date is appropriate, since this is the time when walnuts are still flexible, if one is too late, one may find that the walnuts have hardened, thus making them inappropriate for making Nocino. Nocino mustn’t be tried before the 3rd November, although if the liquor is left to mellow for more than one year the flavour will be richer.
Nocino is also produced in New Zealand by NewZino, under the name "NutZino Walnut Liqueur"  and in Australia by Timboon Railway Shed Distillery in Timboon, Victoria. A handful of craft distillers have started producing the liqueur in the United States, including Watershed Distillery (Columbus, Ohio), Wood Hat Spirits (New Florence, Missouri), Cardinal Spirits (Bloomington, Indiana), Skip Rock Distillers (Snohomish, Washington), and Eda Rhyne Distilling Company (Asheville, North Carolina).
Walnut liquor is also produced in Romania, where it is called "Nucată" and used both recreationally and as a digestive. Besides the walnuts, the recipe includes various combinations of additional flavours, such as anise, black pepper, lemon peel, orange peel, nutmeg or vanilla pods. When making walnut liquor, Romanians sometimes set aside some of the softer walnuts to make walnut jam as well since in June the walnuts are suitable for both uses. In Romania, walnut liquor is sometimes made in autumn as well, out of the green husks of 15-18 walnuts.