A country code constitutes a brief alphanumeric identification system for countries and dependent territories. Its principal application lies within data processing and communications protocols. Multiple identification systems have been developed to serve various purposes[VERIFY]. The term "country code" most commonly refers to ISO 3166-1 alpha-2, alongside telephone country codes, which are standardised through the E.164 recommendation issued by the International Telecommunication Union (ITU).
ISO 3166-1
The standard ISO 3166-1 defines short identification codes for most countries and dependent areas:
- ISO 3166-1 alpha-2: two-letter code
- ISO 3166-1 alpha-3: three-letter code
- ISO 3166-1 numeric: three-digit code
The two-letter codes are used as the basis for other codes and applications, for example,
- for ISO 4217 currency codes
- with deviations, for country code top-level domain names (ccTLDs) on the Internet: list of Internet TLDs.
Other applications are defined in ISO 3166-1 alpha-2.