The source of the following information is from one of my wife's Bibles, "The Archaeological Study Bible."
Romans typically had three names: a praenomen, a nomen and a cognomen. The praenomen was a personal name, the nomen a clan name and the cognomen the name of a particular branch within the clan. Thus, in the name Gaius Julius Caesar, Gaius was the personal name (praenomen), Julius the name of the clan (nomen) and Caesar the name of the extended family or subclan (cognomen) within the Julian clan.
I found this tidbit of ancient history to be interesting. I hope you enjoy. God Bless.. Jerry..