Acountry code is a short alphanumeric identification code for countries and dependent areas. Its primary use is in data processing and communications. Several identification systems have been developed.
The term country code frequently refers to ISO 3166-1 alpha-2, as well as the telephone country code, which is embodied in the E.164 recommendation by the International Telecommunication Union (ITU).
Country codes constitute the international telephone numbering plan, and are dialed only when calling a telephone number in another country. They are dialed before the national telephone number. International calls require at least one additional prefix to be dialing before the country code, to connect the call to international circuits, the international call prefix. When printing telephone numbers this is indicated by a plus-sign (+) in front of a complete international telephone number, per recommendation E164 by the ITU.
FIFA (Fédération Internationale de Football Association) assigns a three-letter code (dubbed FIFA Trigramme) to each of its member and non-member countries: List of FIFA country codes
the first few characters of call signs of radio stations (maritime, aeronautical, amateur radio, broadcasting, and so on) define the country: the ITU prefix,
Under the 1949 and 1968 United Nations Road Traffic Conventions (distinguishing signs of vehicles in international traffic): List of international license plate codes.
North Atlantic Treaty Organization (NATO) used two-letter codes of its own: list of NATO country codes. They were largely borrowed from the FIPS 10-4 codes mentioned below. In 2003 the eighth edition of the Standardisation Agreement (STANAG) adopted the ISO 3166 three-letter codes with one exception (the code for Macedonia). With the ninth edition, NATO is transitioning to four- and six-letter codes based on ISO 3166 with a few exceptions and additions
