locale

Locale refers to a set of parameters that define the linguistic, cultural, and regional conventions used by a software application or by a user. In computing, a locale identifies preferences such as language, country/region, and character encoding, and may include a variant. Locales influence formatting of dates, times, numbers, currencies, and collation order, as well as translation of user interface strings. They enable software to present information in a familiar form for a given audience and to process input according to local rules.

Locale identifiers typically combine components. Common forms include language and region, for example en_US (English as used in the United States), fr_FR, or es_MX. Some systems also include a character encoding (such as .UTF-8) or modifiers (like @currency=EUR). POSIX-style locales use codes like language[_territory][.codeset][@modifier], while Windows uses language culture identifiers (LCID).

Locales are supported by standard libraries and frameworks; for example, the Java Locale class, Python's locale module, and ICU provide data for formatting and sorting according to locale. Web servers may derive locale from the Accept-Language header, while operating systems expose environment variables such as LANG or LC_ALL.

Data underpinning locales come from internationalization efforts such as the Common Locale Data Repository and the Unicode CLDR. Locale data are not universal: a given system may lack a requested locale and fall back to a default. Distinguish locale from location: a locale is about conventions, not geography alone.