languagecode

Languagecode refers to the identifiers used to denote natural languages in computing, data exchange, and metadata. The most widely used standard is ISO 639, which provides two-letter codes (ISO 639-1) and three-letter codes (ISO 639-2 and ISO 639-3) for individual languages. ISO 639-1 covers a subset of widely spoken languages, such as en for English, fr for French, es for Spanish, de for German, and zh for Chinese. ISO 639-2/3 expands to additional languages and variants, including those not represented by two-letter codes.

In modern Internet and software systems, language tags are often defined by BCP 47 (Best Current Practice 47), allowing a language code plus optional script, region, and variant subtags. Examples include en, en-US, zh-Hans-CN, sr-Cyrl-RS, and es-419. These tags, and their registry, are maintained through IANA’s Language Subtag Registry, which records all registered subtags used in BCP 47.

Language codes are used to label content, configure user interfaces, and drive localization workflows. They appear in metadata, URLs, configuration files, APIs, and content management systems to indicate the language of text, audio, or user-facing components.

Challenges include macrolanguages that map to multiple codes, script distinctions, and evolving classifications as languages change. While ISO 639-3 extends coverage beyond ISO 639-1, some languages remain outside easy categorization. Private-use and experimental codes (often starting with x-) allow for non-standard tagging in specific projects. In practice, many systems store either a two-letter code or a full BCP 47 tag, depending on the granularity required.