Definition: Locale is a set of parameters that defines the user’s language, country and any special variant preferences that the user wants to see in their user interface. Usually a locale identifier consists of at least a language identifier and a region identifier.
See FB’s i18n documentation for help. More specifically there is a complete list of supported locales. Unfortunately Australian English isn’t awesome enough to be considered as a separate thing; you’ll be choosing between UK and US English.
PHP Locale Definitions methods
Developing multi language web sites using PHP is actually very easy. A common approach is having an include file for every supported language which contains an array that maps string ids to localized text (for example "WelcomeText" => "Welcome to our homepage." would be included using something like <?= $strings["WelcomeText"] >). However there are several …