Beware. Do not get a ride from any "taxi driver" that approaches you on foot and is parked out of the designated taxi lanes at platform 24 exit at the Roma Termini railway station in Rome. These peolple are scammers. It is best to heed the following when wanting to take a taxi at Roma Termini or elsewhere in Italy.
1) Never go with a taxi driver that approaches you. Stick with the ones that are in designated taxi lanes, ones that you book through your hotel or ones that you book through the FreeNow taxi app.
2) Before putting your luggage in in the taxi make sure the taxi is white with a taxi sign on the door and roof, and that the taxi has both a vehicle license number and taxi driver identification number. (you should write these down or take a photo)
3) Ask the driver what cost the ride is going to be. You should know the approximate cost beforehand. Make sure the driver will take a credit card. Never pay in cash. In addition make sure the taxi meter is turned on once your in the taxi.