How to recognise the region of origin of Italian family names ? Easy, just look at the suffix. Here are a few common ones from North to South.

Piemonte

-ero/ario (e.g. Barbe-ero, Molin-ero, Sobr-ero)
-esio (e.g. Gorr-esio)
-audi/aldi (e.g. Grib-audi, Ramb-audi)
-asco (e.g. Com-asco, Cev-asco)

Liguria

-asco (e.g. Com-asco, Cev-asco)

Lombardia

-ago/aghi/ate/ati (e.g. Air-aghi, Arcon-ato, Gess-ati)
-atti/etti (e.g. Ors-atti, Giorg-etti)
-di/oldi (e.g. Sol-di, Garib-oldi)
-ingo/inghi/enghi/engo (e.g. Martin-engo)

Veneto

-igo (e.g. Bardar-igo)
-acco (e.g. Acco, B-acco, Bazz-acco, Biss-acco, C-acco, Feltr-acco, Pol-acco)
# ending in -l/n/r (e.g. Cana-l, Mani-n, Carre-r)

Fiuli

-otti/utti/ut/ot (e.g. Bertol-otti, Bias-utti, Gregor-utti, Danel-ut,, Franz-ot)

Toscana

-ai/ini (e.g. Ast-ai, Boll-ai, Fornari-ini)
-uoli/aiuoli (e.g. Acciai-uoli, Casci-aiuoli)
-ingo/inghi/enghi/engo (e.g. Martin-engo)

Sardegna

-au (e.g. Bidd-au, Mad-au)
-as (e.g. Cann-as, Pir-as)
-u (e.g. Cafedd-u)

Campania

-isi (e.g. Tro-isi, Pugl-isi)

Sicilia

-isi (e.g. Tro-isi, Pugl-isi)
-aloro (e.g. Fav-aloro, Orgli-aloro)



Let's also note that 40% of Italian surnames are patronymic (from a given name), 35% are topographic (place name), and the remaining 25% are pseudonymic (nick name or descriptive).

Sources