Everyone recognises the word. Far fewer people know that it is one of the oldest living scraps of Latin in daily European speech, or that it reached most of Italy by a route almost nobody expects. Here is where Don comes from, and what it has meant to the people who carried it.
It begins with the Latin for lord
The root is dominus, the Latin word for lord, master, owner of the house. In late and medieval Latin it wore down in speech to domnus, and then to a single blunt syllable: don. The feminine ran the same course. Domina, the lady of the house, became donna. That second word travelled so far into ordinary speech that it is now simply the Italian word for woman, which tells you how thoroughly the old form of address soaked into the language.
How the word came back to Italy
Italians did not inherit Don straight from Rome. It came back to the peninsula later, and it came from Spain. From the thirteenth century the crown of Sicily passed to Aragon; in the fifteenth Naples followed; in the sixteenth Milan and much of the rest of the south came under the Spanish Habsburgs, and for two centuries the larger part of Italy was governed in the Spanish manner, by viceroys sent from a distant court. Spanish court style came with them, and in Spain don was the ordinary honorific of the well born. It took root most deeply where Spanish rule lasted longest, in Sicily, Naples and the south, and it is there that you still hear it every day.
Who was allowed to say it
At first, very few. In medieval Spain the honorific was reserved for royalty and the highest nobility, and using it without the standing to match was a serious presumption. Over the sixteenth and seventeenth centuries it loosened, first to the lesser nobility, then to anyone of visible consequence: the man with the land, the man with the education, the man the town deferred to. By the time the Spanish viceroys were gone it belonged to whoever a community chose to give it to, which is the form it has kept ever since.
It goes before the first name, never the surname
This is the rule most outsiders get wrong, and the one detail that marks out someone who knows the custom. The honorific attaches to the given name. Don Fabrizio, Don Calogero, Donna Angelica. Never the surname. Even a prince follows it: in the great Italian novels the nobleman is addressed by everyone from his priest to his gamekeeper by his first name with Don in front of it, because Don is a courtesy paid to the person, not a rank attached to the house. Our certificates keep the rule.
Donna, and the woman of the house
Donna carried its own weight. It marked the woman who held the household and, very often, the real authority inside it: the one who ran the accounts, arranged the marriages and decided which quarrels were finished. In the south it was a title of respect in the fullest sense, not a decoration borrowed from a husband. Widows in particular kept it for life.
The priest's Don
There is a second line of descent that is still going, and it runs the whole length of the country. Italian secular clergy are addressed as Don plus their first name, so the parish priest is Don Antonio to his whole village, from the Alps to the toe of the boot. That usage is a direct survival of the Latin dominus as a churchman's style, and it is why the most famous fictional priest in Italy is Don Camillo, who lives in the Po valley and has never been near Sicily. In an Italian town you could easily meet two Dons in one street, one in a cassock and one on a bench outside the bar, and both would be using the word correctly.
The word Hollywood borrowed
Most people outside Italy first met the word in a film, attached to a crime boss, and it is worth being straight about that. American cinema borrowed a genuine Italian courtesy and gave it a menace it never had in the villages. The honorific is centuries older than the association, and in Italy it still does its ordinary work: it is what you call an older man you respect, the way you would once have said "sir" and meant it.
Why Don outlived the titles
In 1948 the new Italian Republic wrote the end of the aristocracy into law. Its Constitution declared that titles of nobility are no longer recognised, and with a line of text the princes, dukes and barons of the old order lost their standing in law. Don came through it untouched, and the reason is precise: it was never a rank. It is a form of address, a courtesy, something a community grants rather than a state confers, and there was nothing in it for a constitution to abolish.
What it means on your certificate
That is the tradition our certificates draw on. A Don title of the family, or a Capo or Soldato one, inscribed to a name and sealed with the family rose, in the manner of the old Sicilian families. It is a commemorative title, worn for the pleasure and the story of it, of the same kind the country has handed out by acclaim for four hundred years.