As you run through the terminal you might notice it on your ticket, beside your gate number, or even on a t-shirt. Nearly every airport in the world has a unique three-letter identifier. The signifiers are assigned by the International Air Transport Association, and many reference the airport’s name, or letters in its city’s name. Others are much more obscure.
We’ve gathered a selection of these three-letter codes for some of the world’s busiest airports. Can you tell Charles de Gaulle from Chhatrapati Shivaji?