ISO 3166-1 alpha-2

ISO 3166-1 alpha-2 codes are two-letter country codes in the ISO 3166-1 standard to represent countries and dependent territories. They are published by the International Organization for Standardization (ISO) as part of its ISO 3166 standard. They are the most widely used of the country codes published by ISO, and are used most prominently for country code top-level domains (with a few changes). They were first included as part of the ISO 3166 standard in its first edition in 1974.
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