An airline e-ticket number is a standardized 13-digit code that is unique to every passenger and every journey. The format is strictly regulated by the International Air Transport Association (IATA). The first three digits of the number are known as the "Airline Accounting Code" or "Prefix," which identifies the specific airline that issued the ticket (for example, 001 is American Airlines, 016 is United, and 176 is Emirates). The following ten digits constitute the unique serial number for that specific transaction. This number is different from your PNR (Passenger Name Record) or "Booking Reference," which is usually a 6-character alphanumeric code like "AB12CD." While the PNR identifies your entire reservation (which might include multiple people), the e-ticket number is tied specifically to the individual payment and the "coupon" used for each flight segment. You can usually find this 13-digit number on your receipt or boarding pass. It is essential for managing your booking, requesting refunds, or claiming frequent flyer miles. If you ever have trouble finding your flight in an airline's system using your name or PNR, providing the 13-digit e-ticket number is the most definitive way for the airline to locate your specific travel record and payment status.