A lot of European cities have a bus and subway system, of course some cities have more than others, and Rome has a fair share of buses even though it is not the best, but because of the traffic, accidents and other outside factors such as strike (always check if there are strikes going
on) or summer hours, always be prepared to wait at least 10-15 minutes, so plan your day accordingly.
First thing is to decide what type of bus fare to buy, you have several choices. There is the ticket for 1 Euro which lasts 75 minutes, the daily ticket for 4 Euros, or a 3 day ticket for 11 Euros and the weekly ticket for 16 Euros (there is also a monthly one for 30 Euros but unless you stay for an entire month this is not worth it).
While using the subway, remember that the 1 Euro ticket will be valid only for one subway trip, but the wait underground is less, between two to four minutes during high peak times and about five for slower moments of the day, so sometimes it is best to get different kinds of tickets depending on the situation. Rome has two lines of subways, the A and the B and they connect at the Termini stop, which is the main train station also; the hours of operation for the subway are from 5:00 A.M to 11:00 P.M Sunday through Thursday and Friday and Saturday s from 5:00 A.M to 1:30 A.M.
There are also city trains that go around the city and in the outskirts and also to the airport, and you can use the same A.T.A.C tickets that you buy for the buses or subways, these are great if you end up staying in a bed and breakfast that is further out than the ones in the city center, a few of them go to the lakes right outside Rome, where a lot of people enjoy their weekends at. While the city center has several buses that go through it as well as the subway which has 4 or 5 main stops in the center such as Barberini (via Veneto), Spagna (Spanish Step), Flaminio (Via del Corso) and so on. And there are also some bus lines that travel at night from midnight until 5:00 A.M, they do not stop often but it is good to know that they are there because Taxi’s can be expensive, and a lot of stops, mainly in the city center have signs that tell you how far away is the bus from your stop.