In 2026, choosing a seat on a train is almost always done during the online booking process through the rail operator's website or a mobile app like Trainline or Omio. For long-distance and high-speed services (like Eurostar, TGV, or Amtrak), you are often presented with a graphic seat map similar to an airline's, allowing you to select a window seat, an aisle seat, or a seat with a table. In the UK, operators like LNER and Avanti West Coast allow you to specify preferences (e.g., "quiet carriage," "near power socket") if a map isn't available. If you have already purchased a ticket without a reservation, you can sometimes go back into the "Manage My Booking" section to add one. On many regional or commuter "turn-up-and-go" trains, seats cannot be reserved, and it is first-come, first-served. For 2026 travelers, the "pro-tip" is to check the electronic displays above the seats once on board; a green light or a "Available" message means you can sit there, while a red light indicates the seat is reserved for a passenger boarding at a later station.