An IATA airport code, also known an IATA location identifier or station code, is a three-letter code designating many airports around the world, defined by the International Air Transport Association (IATA).
Assignment of these codes is governed by IATA Resolution 763 and is administered by IATA headquarters in Montreal.
The codes are published biannually in the IATA Airline Coding Directory. The codes are unique at any given point in time, although defunct codes may be re-used after a suitable period of time has elapsed.

The ICAO airport code or location indicator is a four-letter alphanumeric code designating each airport around the world. These codes are defined by the International Civil Aviation Organization (ICAO).
The ICAO codes are used by air traffic control and airline operations such as flight planning. They are not the same as the IATA codes which are used for airline timetables, reservations, and baggage handling. ICAO codes are also used to identify other locations such as weather stations, International Flight Service Stations or Area Control Centres.

Unlike IATA codes, ICAO codes have a regional structure, are not duplicated and are comprehensive. In general, the first letter is allocated by continent and represents a country or group of countries within that continent. The second letter generally represents a country within that region, and the remaining two are used to identify each airport. The exception to this rule is larger countries that have single-letter country codes, where the remaining three letters identify the airport.
In the United States and Canada, most ( but not al) airports have been assigned three-letter IATA codes which are the same as their ICAO code without the leading K or C. However, because Alaska, Hawaii and other United States territories have their own 2-letter ICAO prefix, the situation there is similar to other smaller countries and the ICAO code of their airports is typically different from its corresponding 3-letter FAA/IATA identifier. In region L (Southern Europe), all available 2-letter prefixes have been exhausted and thus no additional countries can be added.

A - Western South Pacific
AG      Solomon Islands
AN      Nauru
AY      Papua New Guinea

B - Iceland/Greenland
BG      Greenland
BI        Iceland

C - Canada
C       Canada

D - West Africa
DA      Algeria
DB      Benin
DF      Burkina Faso
DG     Ghana
DI       Côte d'Ivoire
DN      Nigeria
DR       Niger
DT       Tunisia
DX      Togolese Republic

E - Northern Europe
EB       Belgium
ED       Germany
EE        Estonia
EF        Finland
EG       United Kingdom
EH       Netherlands
EI         Ireland
EK       Denmark
EL       Luxembourg
EN       Norway
EP        Poland
ES       Sweden
ET       Germany (military)
EV       Latvia
EY       Lithuania

F - Southern Africa
FA        South Africa
FB        Botswana
FC        Congo, PR
FD         Swaziland
FE         Central African Republic
FG        Equatorial Guinea
FH        Ascension Island
FI          Mauritius
FJ         British Indian Ocean Territory
FK        Cameroon
FL        Zambia
FM        Comoros, Madagascar
FM        Mayotte, Réunion
FN        Angola
FO        Gabon
FP        Sao Tomé and Príncipe
FQ        Mozambique
FS        Seychelles
FT        Chad
FV        Zimbabwe
FW       Malawi
FX        Lesotho
FY        Namibia
FZ        Congo, DR

G - Northwestern Africa
GA       Mali
GB       The Gambia
GC       Canary Islands (Spain)
GE       Ceuta and Melilla (Spain)<

GF       Sierra Leone
GG       Guinea-Bissau
GL        Liberia
GM       Morocco
GO       Senegal
GQ       Mauritania
GS       Western Sahara
GU       Guinea
GV       Cape Verde

H - Northeastern Africa
HA      Ethiopia
HB      Burundi
HC      Somalia
HD      Djibouti (also HF)
HE      Egypt
HF      Djibouti (also HD)
HH      Eritrea
HK      Kenya
HL      Libya
HR      Rwanda
HS      Sudan
HT      Tanzania
HU      Uganda

K - USA
K       USA

L - Southern Europe
LA     Albania
LB     Bulgaria
LC     Cyprus
LD     Croatia
LE     Spain
LF     France (+St Pierre & Miquelon)
LG     Greece
LH     Hungary
LI       Italy
LJ      Slovenia
LK      Czech Republic
LL      Israel
LM     Malta
LN      Monaco
LO     Austria
LP      Portugal, Azores
LQ     Bosnia & Herzegovina
LR     Romania
LS     Switzerland
LT     Turkey
LU     Moldova
LV     Gaza Strip
LW    Macedonia
LX     Gibraltar
LY     Serbia
LZ     Slovakia

M - Central America
MB     Turks and Caicos Islands
MD     Dominican Republic
MG     Guatemala
MH      Honduras
MK      Jamaica
MM      Mexico
MN      Nicaragua
MP      Panama
MR      Costa Rica
MS      El Salvador
MT      Haiti
MU      Cuba
MW     Cayman Islands
MY      Bahamas
MZ      Belize

N - South Pacific
NC       Cook Islands
NF       Fiji, Tonga
NG       Kiribati (Gilbert Islands)
NG       Tuvalu
NI         Niue
NL        Wallis and Futuna
NS       Samoa
NS       American Samoa
NT        French Polynesia
NV       Vanuatu
NW       New Caledonia
NZ        New Zealand
NZ       Antarctica

O - Southwest Asia
OA       Afghanistan
OB       Bahrain
OE       Saudi Arabia
OI         Iran
OJ        Jordan & the West Bank
OK       Kuwait
OL       Lebanon
OM       United Arab Emirates
OO       Oman
OP       Pakistan
OR       Iraq
OS       Syria
OT       Qatar
OY      Yemen

P - Eastern North Pacific
PA       Alaska
PB        Baker Island
PC        Kiribati
PF        Fort Yukon, Alaska
PG       Guam
PG       Northern Marianas
PH        Hawaii
PJ        Johnston Atoll
PK        Marshall Islands
PL        Kiribati (Line Islands)
PM       Midway Island
PO       Oliktok Point, Alaska
PP        Point Lay, Alaska
PT        Micronesia, Palau
PW       Wake Island

R - Western North Pacific
RC       Taiwan
RJ        Japan
RK        South Korea
RO       Japan (Okinawa; Yoron)
RP        Philippines

S - South America
SA        Argentina
SB        Brazil (also SD, SN, SS, SW)
SC        Chile
SD        Brazil (also SB, SN, SS, SW)
SE        Ecuador
SF        Falkland Islands
SG       Paraguay
SK       Colombia
SL       Bolivia
SM      Suriname
SN       Brazil (also SB, SD, SS, SW)
SO       French Guiana
SP       Peru
SS       Brazil (also SB, SD, SN, SW)
SU       Uruguay

SV      Venezuela
SW      Brazil (also SB, SD, SN, SS)
SY      Guyana

T - Caribbean
TA     Antigua and Barbuda
TB     Barbados
TD     Dominica
TF     Guadeloupe
TG     Grenada
TI       U.S. Virgin Islands
TJ      Puerto Rico
TK     Saint Kitts and Nevis
TL     Saint Lucia
TN     Netherlands Antilles, Aruba
TQ     Anguilla
TR     Montserrat
TT     Trinidad and Tobago
TU     British Virgin Islands
TV     Saint Vincent & the Grenadines
TX     Bermuda

U - Russia; former Soviet States
U       Russia
UA     Kazakhstan, Kyrgyzstan
UB     Azerbaijan
UD     Armenia
UG     Georgia
UK     Ukraine
UM     Belarus
UT      Tajikistan, Turkmenistan
UT      Uzbekistan

W - Maritime Southeast Asia (except the Philippines)
WA     Indonesia (also WI, WQ, WR)
WB      Malaysia (also WM)
WB      Brunei
WI       Indonesia (also WA, WQ, WR)
WM     Malaysia (also WB)
WP      Timor-Leste
WQ     Indonesia (also WA, WI, WR)
WR     Indonesia (also WA, WI, WQ)
WS     Singapore

Y - Australia
Y        Australia

Z - China, Mongolia, North Korea
Z        China (except ZK and ZM)
ZK      North Korea
ZM      Mongolia