Online train ticket reservations

In Italy, that is it plus ID (passport). If you bought a ticket in Germany through Deutsche Bahn, you will also need to have the same credit card as you used to buy the ticket. That is how you prove its your ticket and not a resale. France same as Italy.

What you need with your online ticket depends on the country and the kind of ticket. "Europe" is more than one country, and therefore there is more than one system. For Italy, you're set. The PDF is your ticket. For Germany, in addition to the printed PDF, you need the credit card you used to buy the ticket. On the train, the conductor scans the PDF and swipes your credit card. For France, if you have a print-at-home ticket, you need that plus your passport. On the train, the conductor matches your passport to your ticket, then scans the printed PDF. For all of these, you do not need to get another ticket; your printed PDF is your ticket. Some of them are also starting to implement ways to have the PDF on your phone so you don't have to print it out. If you are picking up a French ticket at a French ticket office, you need the credit card you used to book the ticket. However, once you have picked up this ticket, you don't need anything else on the train; you just have to remember to "composte" the ticket ( it into the yellow machine near the tracks) before using it.

Thank you very much both of you!