To determine if your checked luggage will be automatically transferred to your final destination, you must first look at your itinerary and ticket structure. Generally, if all your flights were booked under a single ticket and booking reference (PNR) with the same airline or partner airlines (such as those in the Star Alliance, SkyTeam, or Oneworld alliances), your bags will be "checked through." You can verify this during the initial check-in process; the agent will confirm the final destination, and the luggage tag printed and attached to your bag will display the final airport code. If you have booked two separate tickets (a "self-transfer"), you will almost always need to collect your bags at the intermediate airport, clear customs, and check them in again for the next leg. For international travel, even on a single ticket, certain countries (like the United States) require all passengers to collect their luggage at the first port of entry to clear customs before placing it back on a transfer belt for the connecting flight.