String API
From MoodleDocs
The String API is how you get language text strings to use in the user interface. It handles any language translations that might be available.
Places_to_search_for_lang_strings was the existing documentation on this.--Tim Hunt 16:04, 11 January 2012 (WST)
Also, I don't really like the name 'String API'. That sounds very low-level to me. PHP already has one. Internationalisation API, or Translation API, might be better.--Tim Hunt 16:04, 11 January 2012 (WST)