A Locale represents a specific geographical, political, or cultural entity. It encapsulates user interface language, date and time formats, number and currency formats and other settings. Locales consist of a language with an optional region identifier, for example: English (British) en_GB or German (Germany) de_DE.
This guide covers the customization of currency, date and time formats, address formats and other non-linguistic aspects of a given locale.
It does not cover how to translate the user interface of the application.