Question: what is nosb in train ticket?
Answer: In IRCTC, NOSB stands for No Seat Berth; in other words, it means no seat for half fare. In general, if you happen to book a ticket for your children aged between 5-12 years, they can board the train, but cannot occupy the seat. You have to pay the full amount irrespective of the age to get the confirmed berth/seat.