i18n, l10n and translation
Open source program translation to user’s own language
I18n (internationalization) and l10n (localization) provide the method. Each language can define in language_nation.po. For example, Korean po file are ‘ko_KP.po’ (north Korea) and ‘ko_KR.po’ (south Korea) or ‘ko.po’.
po editor can add translation into po file. There are many po editor with cross-platform (MS windows, Linux, Mac) - poEdit, Kbabel, etc. Pootle is web based po translator.
Ubuntu use the Rosetta Translation Portal - https://launchpad.net/rosetta