A PNR (Passenger Name Record) number is a unique reservation number or booking number issued by the airline for one or more flights. It is a combination of six alphanumeric characters that is generated at the time of booking a flight ticket. The PNR number is used to keep track of all the details related to a particular passengers booking, such as itinerary, seat assignment, contact details, etc. It is also used as a booking confirmation and a repository of valuable commercial information. The PNR number is usually printed at the top of a flight ticket, next to the flight number, and might be labeled as "Record Locator" or "File Reference". It can also be found on the e-ticket in the corresponding segment of the itinerary. It is important to note that there can be a different PNR number for each part of the trip, especially for separate bookings or for stopovers with their own transfer. In most cases, the PNR number is also the booking number.