Remember to read the "Stay safe section". Better to have a local guide in Naples, otherwise you may get in troubles.
Both Naples and the locally Italian Napoli are acceptable; either way, it's a derivative of the ancient Greek name Neapolis, which means new city. The Greeks first established the city and inhabited the region long before Roman times. The most widely spoken language in Naples is Italian or a mixture of Italian and Napulitano (Neapolitan). Neapolitan is sometimes described as an Italian dialect, but may be considered a separate language and can sometimes be unintelligible to the general Italian speaker. Neapolitan does not enjoy any official status, but it does have a rich literary tradition and it is still thriving in Campania and adjacent parts of Lazio, Abruzzo, Basilicata, Molise and Calabria. This said, the official language of Naples (as of all of Italy) is Italian and everyone speaks it. Neapolitan has strong Spanish and French influences originating from their occupation of the area. Therefore, more Spanish and French words are understood by the locals than in other parts of Italy. English is the most commonly spoken foreign language, although the average knowledge of English is far from excellent.