The best way to find a taxi in Rome is generally to hire a taxi at a taxi stand. Taxis do not cruise, but if free they may stop if you flag them down. They wait at stands, but can also be called by phone, in which case you're charged a supplement (the meter will already be running when you’re picked up). The various taxi services are considered interchangeable and are referred to by their phone numbers rather than names. Taxicabs can be reserved the night before only if you're traveling to or from the airport or the train station. Only some taxis are equipped to take credit cards; inquire when you phone to make the booking.
The meter starts at €3 during the day, €6.50 10 pm–6 am, and €4.50 on Sunday and holidays. Supplemental charges, such as for luggage or even for pick up at Termini station, are added to the meter fare. When in doubt, ask for a receipt (ricevuta). This will encourage the taxicab driver to be honest and charge you the correct amount. Women traveling alone via taxi 10 pm–6 am are entitled to a 10% discount; the same discount applies if your destination is a public hospital. (Make sure to ask for it.) Use only licensed, metered white cabs, identified by a numbered shield on the side, an illuminated taxi sign on the roof, and a plaque next to the license plate reading "servizio pubblico." Avoid unmarked, unauthorized, unmetered cabs (numerous at Rome airports and train stations), whose drivers actively solicit your trade and may demand astronomical fares.
While ride-sharing apps like Uber and Lyft are not yet big in Rome, a new app, Mytaxi, is a quick and easy way to book an official taxi with a smartphone. You can choose to pay by app or with cash, and can rate your driver after the ride.