The main railway in Italy is Trenitalia, run by the Italian government. Trenitalia handles the vast majority of passenger train travel in the country, including the high-speed Alta Velocità (AV) trains. There are also some cross-border trains operated at least in part by Trenitalia, serving cities in Switzerland and France.
Italo is a much newer railway in Italy, currently operating only high-speed trains to a limited (but growing) number of cities. Italo and Trenitalia sometimes use different stations in the same cities.
The Thello railway is a joint venture between Trenitalia and a French railway, and it serves solely to connect cities in the two countries. TILO serves a similar purpose between Italy and Switzerland.
There are also smaller regional railways, including Trenord in Lombardy, which is partly owned by Trenitalia, and the Circumetnea that runs along the base of Mt. Etna in Sicily.