Internationalization
Translate UI strings, negotiate locale, and query core's locale support.
The i18n module provides gettext / pgettext / ngettext-style lookups, CLDR plural categories (plural_category / translate_plural for Slavic few/many forms), negotiate_language (Accept-Language), language_display_name, and is_rtl. The capability registry — locale_info(code) and known_locales() — reports what core statically knows about a locale (display name, RTL, plural rules) so apps managing their own locale roster can validate codes and degrade gracefully.
This very site is built on rustango-cms, which layers content localization on top: cms_locale rows managed in the admin, per-field cms_translation overrides applied automatically by the render engine (pages, StreamField bodies, menus, snippets), a language_switcher() Tera function, <head> hreflang alternates, and per-locale sitemap entries (see the language switcher above).
This site is multilingual
Use the EN / FR / DE / UK / 中文 switcher in the header — the Installation page is fully translated as a live demo.