While message catalogs allow you to localize any messages in your application, there are a number of strings that are used in many applications for which translations are readily available.
Imagine for example you have a list of countries that users can choose from, and you'd like to display the names of those countries in the language the user prefers. Instead of translating all those country names yourself in your application, you can make use of the translations provided by the locale data included with Babel, which is based on the Common Locale Data Repository (CLDR) developed and maintained by the Unicode Consortium.
You normally access such locale data through the Locale class provided by Babel:
In addition to country/territory names, the locale data also provides access to names of languages, scripts, variants, time zones, and more. Some of the data is closely related to number and date formatting.
Most of the corresponding Locale properties return dictionaries, where the key is a code such as the ISO country and language codes. Consult the API documentation for references to the relevant specifications.
The Locale class provides access to many locale display names related to calendar display, such as the names of week days or months.
These display names are of course used for date formatting, but can also be used, for example, to show a list of months to the user in their preferred language: