What is pnr number in flight ticket?

Right, the PNR is basically your booking reference. PNR stands for 'Passenger Name Record'. It's a unique code the airline gives you for your specific trip.

You'll find it printed on your e-ticket or in the confirmation email you got after booking. It's usually six characters long, a mix of letters and numbers, like ZK5P2X for example.

This number is very useful. You need it to manage your booking online. So if you want to check-in, choose a seat, or just look at your flight details, you use the PNR. It holds all your information for that journey. It connects your name to the specific flights you've paid for. So yeah, it's quite important. Cheers.