ISO 3166-1 alpha-2 code
The two-letter country code in part 1 of the ISO 3166 standard, such as DE for Germany or BR for Brazil.
An alpha-2 code names a country. It is the shortest of the three renderings ISO 3166-1 defines and the one most data exchange uses, which is also where country domain names come from.
It identifies the country only. A state, province or region inside it carries an ISO 3166-2 code, which is built on top of the alpha-2 code.
The same country also has an alpha-3 code and an ISO 3166-1 numeric code. The three say the same thing in different notations and never disagree.
