Neapolitan (autonym: nnapulitano; Italian: napoletano), also known as Neapolitan–Calabrian, is the language of southern continental Italy, including the city of Naples. It is named not after the city, but after the Kingdom of Naples, which once covered most of this area and of which Naples was the capital.
Neapolitan has had a significant influence on the intonation of Rioplatense Spanish, of the Buenos Aires region of Argentina.
The rest of southern continental Italy speaks a language that is catalogued as Sicilian.
The reality is that a long while back, the two languages were one. Then historical reasons have favourited a faster latinisation in the regions that now speak Neapolitan; the remaining continental regions and Sicily remained more isolated in their Greek influence.
Today the two languages have still many features in common, but also very distinctive features. The language spoken in Terra d’Otranto (Salento) serves beautifully as a bridge between the two.