There were hundred of posts about this subject.
There is no problem to buy train tickets while you are in Italy, and this the best option.
You can look in advance in Trenitalia to know what trains are, their schedule and to make your plans based on the time of the departure and arrival. But nothing more than this is requested.
You can not reserve seats for all trains, for instance, Regionale (local) trains have not this option.
There are other trains, faster and on longer distances, where there is reservation, but it is not a must. If you have luggages it is good to buy the seat.
There are other trains where you must have the seat reservation.
Any case, you can do this in Italy, in the day when you travel or some days in advance.

Trenitalia won't accept most US credit cards. I don't know of anyone recently that has been able to purchase online. If you were able to purchase, they do not mail tickets. You would print the code yourself. As for seat selection, on Trenitalia, the selection is if you are wanting to book a ticket next to a previously purchased ticket.

>>>>There are other trains, faster and on longer distances, where there is reservation, but it is not a must. If you have luggages it is good to buy the seat.
There are other trains where you must have the seat reservation.<<<<

All trains in Italy (except R trains) are now mandatory reserved seat. You can not reserve a seat on R trains even if you wanted.

Buy your train tickets upon arrival in Italy. You can buy them at any train station including the station at the Rome Fiumicino airport or at a travel agency that displays the Trenitalia logo. Almost all travel agents speak English.

I usually print out a schedule for the trips I want to buy, then I can show that at the window. Also there are (supposedly, but I have not tried) easy to use machines at the stations to buy your tickets.

So do those machines take US credit cards?????

The Trenitalia ticket machines do take US magnetic strip credit cards.

I would also add that there can be lines at the ticket machines depending on the station and the time and also who are ahead of you. I had an experience in a small station where I could see only two machines with about 10min long lines each when I got in one. The guy at one machine was trying to buy tickets using a 50Eu bill and the machine kept spitting it out. He did not give up much to be dismay of the people waiting in line. Everyone was happy when the machine finally accepted his bill. The other machine had a family taking just as long time trying to figure out how to buy tickets.

I have read postings about using the machines to avoid the lines, but lines can exist at the ticket machine also.

At large stations, such as Rome's Termini, there are rows of ticket machines (towards the front entrance - not within sight of the tracks). You will have no trouble finding an empty one. Some machines will be cash only, but are clearly marked as such. They are touch screen in English and will take your credit card. There are a couple of random machines trackside at Termini, but they are the old type and cash only.

In smaller stations, the machines will likely be the old type and a bit more difficult to use.

Well just wondering why the machines will take US credit cards and the website will not - I sure would like to buy the advance fare tickets and save some E's! I think some of the routes served by the fast trains have gotten a bit pricey - I'm used to Italian trains being a bargain!

Will be traveling between Naples and Rome via train and will be traveling sometime in the afternoon. Is it necessary to buy a ticket for a specific train or are "open" tickets typically available?

Charlotte, we are going to be in Rome celebrating our granddaughter's 13th birthday from June 15-20. Might we explore the possibility of meeting for dinner one night? I don't know how to contact a forum member directly, so email me at kwedl@comcast.net if interested. We are also looking to travel by train.

suec1 wrote--"just wondering why the machines will take US credit cards and the website will not"

I assume because when you use the machine at the station, you actually scan your credit card. When you buy online, you just need the credit card number. Using the actual card is probably considered more secure.

Weekender asked-"Is it necessary to buy a ticket for a specific train or are "open" tickets typically available?"
Regionale trains designated by R have tickets for any train to your destination. All other trains now offer tickets that are for a specific seat on a specific train.

Ellenem:

Thank you. That is exactly the info I need.

>>>Will be traveling between Naples and Rome via train and will be traveling sometime in the afternoon. Is it necessary to buy a ticket for a specific train or are "open" tickets typically available?<<<

Yes. Most trains (AV/ES/ICPlus/IC)are reserved seat only. You can't get on just any train and sit where you want because you are purchasing a specific seat. R trains, which are the slowest and make the most stops, are the only trains that aren't reserved seating anymore.

We purchased from their website and within a week I had my tickets in the mail to Wisconsin.

>>>AMYWISS on Apr 7, 10 at 11:39am
We purchased from their website and within a week I had my tickets in the mail to Wisconsin.<<<

From what website? Trenitalia states they only mail in Italy.

>Home delivery
The home delivery service is provided by registered letter and involves an extra cost of 3.35 euro, on top of the ticket price. The home delivery takes 4 to 6 days and is only on weekdays and only in Italy.

Amywiss certainly wasn't using Trenitalia.com. And no other site can sell the cheap tickets.

After trying 10 different American Credits cards, I called Trenitalia their phone number is Tel. +39 06 68475475 they indicated they only take Italian Credit Cards via their website.