These are just IATA (International Air Transport Association) codes. They are used in aviation to identify and differentiate airports. That’s why a New York LaGuardia Airport to Reykjavik Keflavik Intl Airport flight would often be abbreviated as a LGA to KEF flight. This flight route has multiple associated airports, so we think it might be helpful to learn the name and codes of them as well. They are Reykjavik Domestic Airport (RKV).