EMZETT.Country Codes
In short: Standardised abbreviations for countries, usually following ISO 3166-1 — the basis for ccTLDs like .de (Germany) or .fr (France).
In more detail: There are two- and three-letter variants (alpha-2 and alpha-3); only the two-letter alpha-2 code is used for ccTLDs. Country codes also appear outside DNS, e.g. in telephone dialling codes or IBAN numbers.
In Depth
ISO 3166-1 has three parallel encodings for the same country:
| Format | Example: Germany | Typical use |
|---|---|---|
| Alpha-2 | DE | ccTLDs, country prefixes in IBAN |
| Alpha-3 | DEU | international forms, sports federations |
| Numeric | 276 | statistical systems, older databases |
The alpha-2 codes are historically closely tied to ccTLDs — when DNS was introduced in the early 1980s, it made sense to use the already-existing ISO standard as the basis for country-specific domain endings, instead of inventing a completely new abbreviation system. Not every country code intuitively matches the common name — .ch for Switzerland comes from “Confoederatio Helvetica”, the Latin name of the state, not the English “Switzerland”.