google DSA airport. It's the number one item.
Failing that I google xyz IATA and that is better for the more obscure ones.
Time to learn something useful is under five seconds. If you get LHR and LGW why stop there? I could be sad and ramble that there's a whole world of learing why Orlando is MCO as it was once McCoy AFB and why Tees-side is MME.....
IATA codes are easy. ICAO ones not so much, certainly in the UK