An airline PNR (Passenger Name Record) code, often called a booking reference or confirmation code, is typically a six-character alphanumeric string. This unique identifier is generated by a Global Distribution System (GDS) or an airline's internal reservation system at the time of booking. It can consist of both uppercase letters (A–Z) and numbers (0–9), though some airlines specifically avoid using numbers that look like letters (such as 0/O or 1/I) to prevent confusion. For example, a PNR might look like "XJ3K9P." However, there are exceptions; some specific regional carriers or state-owned airlines, like Air India, have been known to use a 10-digit numeric or alphanumeric PNR for their internal tracking. Despite these variations, the industry standard for most international and domestic carriers remains the six-digit code. This PNR is the master key to your travel data, linking your name to your itinerary, seat selection, meal preferences, and payment details. You will find it on your e-ticket or in your airline’s mobile app, and you should keep it private, as it can be used to access sensitive personal information or modify your booking.