ISO 3166-1 Alpha-2 - Country Codes
ISO 3166-1 defines codes for the names of countries, territories, and other special areas of geographical interest. It is part of the ISO 3166 standard published by the International Organization for Standardization (ISO). ISO 3166-1 is broken down into 3 sets of country codes: ISO 3166-1 Alpha-3, ISO 3166-1 Alpha-2, and ISO 3166-1 Numeric.
ISO 3166-1 Alpha-2 are two-letter country codes and are the most widely used of the three.
ISO 3166-1 Alpha-2 country codes are commonly used for such things as the Internet’s country code top-level domains, currency codes, and bank identifier codes.