Languages
Manage default and active site languages and understand the language record.
The language manager owns the configured language set. A language record includes its code, WordPress locale, BCP 47 tag, native and English names, text direction, active/default flags, display order, and home URL.

Default language
The default language keeps the site’s existing URL shape. Other active languages may use a language directory such as /tr/. Changing the default language is a routing decision; make it with a redirect and rollback plan.
Active versus configured
The public REST language read returns active languages by default. A privileged request may ask for all configured languages. Inactive languages are configuration, not a public promise that content is served in that language.
Direction
The language record exposes ltr or rtl. Themes and integrations should use this value rather than infer direction from a country or language name.