One of the best articles I have read about Italian Surnames was the Life in Italy website and written by By Elizabeth Walling. A piece extracted from the article follows below.
Delving into the research of surnames, also known as last names or family names, is an exciting way to learn more about your family history. When researching Italian surnames, you will quickly find that each family name in Italy was formed for a particular purpose. Italy has always been known for its lively and extraordinary land and people, and Italian names exhibit these same qualities.
In the age of ancient Rome, individuals were named in three parts. These parts included a basic first name, a name in which a person’s family was identified, and also a unique name that described that individual.