- ISO 3166-1
- An international standard published by the International Organization for Standardization that defines codes for the names of countries, dependent territories, and special areas. Alpha-2 (two-letter) and alpha-3 (three-letter) codes are the most widely used variants.
- Alpha-2 Code
- A two-letter country code from the ISO 3166-1 standard (e.g., US, GB, JP). These are the most widely used country identifiers in software, appearing in locale strings, domain suffixes (ccTLDs), and international APIs.
- Alpha-3 Code
- A three-letter country code from the ISO 3166-1 standard (e.g., USA, GBR, JPN). Used in passports, sporting event databases, financial systems, and international statistics.
- UN Member State
- One of the 193 countries that are full members of the United Nations, representing the most internationally recognized set of sovereign nations. The tool's pool adds Vatican City and Palestine as observer states for a total of 195.
- Flag Emoji
- Unicode characters representing national flags, encoded as sequences of Regional Indicator Symbol Letters (e.g., the UK flag is the sequence 🇬🇧 formed from the letters G and B). Support varies by operating system and application.
- ccTLD (Country Code Top-Level Domain)
- An internet domain suffix assigned to a country based on its ISO 3166-1 alpha-2 code (e.g., .jp for Japan, .de for Germany). Closely related to but not always identical to the alpha-2 code in use.