ISO 3166-1 Alpha-3 - 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-3 are three-letter country codes which allow for over 17,000 unique combinations. Additionally, there is a better connection between the codes and the country names than the Alpha-2 codes because of the extra character.
ISO 3166-1 Alpha-3 country codes are commonly used for such things as machine-readable passports and international vehicle registration codes.