The consulted works concur in identifying Giovanni as one of the most widespread given names in Italy and the source of a large family of surnames. Both A. Bongioanni and E. De Felice trace the name to the Hebrew Yôḥānān, meaning "God has been merciful," noting that it entered European usage through the Greek and Latin form Ioannes. The two scholars agree that the name's exceptional popularity derives from early Christian devotion, above all to Saint John the Baptist and Saint John the Evangelist, and that from this single given name a vast cluster of surnames developed across all of Italy. It is also recorded that the name derives from the Hebrew Yohanan, composed of Yahwè ("God") and hanan ("to be merciful").

Bongioanni and De Felice together describe a first group of surnames that preserve the full or nearly full form of the name, without passing through the shortened variants Gianni, Nanni, or Zanni. The surname Giovanni itself is infrequent and documented mainly in southern Italy; Di Giovanni is a patronymic typical of the south, meaning "son of Giovanni." The forms Giovannini, Giovannetti, and Giovannelli, built with the suffixes -ini, -etti, and -elli, are widespread in central and northern Italy. Giovannoni, carrying the augmentative suffix -oni, is common in Tuscany and Lazio, while Giovannozzi is a Tuscan form with an affective plural suffix. Della Giovanna, a family form, is frequent in Lombardy. These scholars note that such suffixes are characteristic of Italian patronymic formation and reflect nuances of filiation, relative size, or family belonging.

Bongioanni and De Felice further observe that in spoken use Giovanni rarely survived intact: in many regions it was shortened, giving rise to briefer forms that in turn generated additional groups of surnames. Those derived forms beginning with Nanni, Vanni, and Zanni are treated in their respective entries.