The common prefixes of Italian surnames have at least three different sources.
1) Patronyms: The prefix "di" (meaning "of" or "from") is often attached to an otherwise ordinary christian name to form a patronym. di Benedetto (for example) is the Italian equivalent of Benson, di Giovanni is Johnson, and di Miceli is Michaleson. Most ineteresting is the fact that such patronyms often derive not from the name of a paternal ancestor, but from a favored saint or religious figure. Saint Dominic (for example) the founder of the Dominican order gives us di Domenico, Didomenici, Menico, Menicossa... literally hundreds of related patronyms.
2) Location: The prefixes "da" and "di" (again meaning "of" or "from") are often associated with a place of origin. Examples include da Vinci and di Napoli. This aften evolved from a nickname for someone who was "from" a place, but no longer lived there.
3) The prefixes "la" and "lo" (meaning "the") was often derived from nicknames. Giacomo la Greca, for example, means Jimmy the Greek. But in the mid 19th century, the prefix was widely attached to older names in Sicily (at least) where it meant "of the family of." For example, my Furia ancestors began naming their children la Furia, meaning "of the family Furia." It was quite a fashionable thing to do, and the name stuck. At the same time, the Licata family was becoming la Licata, the Greco family was becoming lo Greco, it was an absolute epidemic.
Over time, the prefixes could often be dropped again, or sometimes combined to become a single name (like Dimiceli, or Diliberto). Often siblings would go through lives with different forms, or change them almost willy nilly from one document to the next.
Author, Evangelos P. Kordakis
DesignLabs Web Solutions
1999