A flight reservation number, also known as a Passenger Name Record (PNR) or booking reference, is typically a six-character alphanumeric code (e.g., G4H7Y2 or BND89L). This unique identifier is assigned by the airline's global distribution system at the time of booking and is required for checking in online or managing your flight. It is important to distinguish this from your "Ticket Number," which is a longer 13-digit numeric string (e.g., 0061234567890), or your "Flight Number" (e.g., UA123), which identifies the specific scheduled service. Your PNR code is usually prominently displayed in your confirmation email or on your electronic boarding pass. Because this code, combined with your last name, can grant access to your sensitive personal data and the ability to change or cancel your flight, you should never share photos of it on social media.