To "board" using an online train ticket in 2026, the process has become almost entirely paperless across major networks like Amtrak, Eurostar, or Renfe. First, you purchase your ticket through the operator's app or website, which generates a QR code. You do not necessarily "board" the ticket itself; rather, you use the QR code to gain access to the platform or to show the conductor. At most modern stations, you will find glass barriers with scanners; simply hold your phone screen with the QR code facing the scanner to open the gate. Once on the train, keep your phone accessible. A conductor will eventually walk through the cabin and ask to see your ticket; they will use a handheld device to scan your code again. It is highly recommended to save the ticket to your "Apple Wallet" or "Google Wallet" or take a screenshot, as cell service can be spotty in tunnels or rural areas, and you don't want to be unable to retrieve the code when the inspector arrives. If your phone battery is low, many stations have kiosks where you can enter your "Booking Reference" to print a physical backup copy.