Language localization and Language codes

The localization process is most generally related to the cultural adaptation and translation of software, video games, websites, and technical communication, as well as audio/voiceover, video, or other multimedia content, and less frequently to any written translation (which may also involve cultural adaptation processes). Localization can be done for regions or countries where people speak different languages or where the same language is spoken. For instance, different dialects of German, with different idioms, are spoken in Germany, Austria, Switzerland, and Belgium.

Language codes are closely related to the localizing process because they indicate the locales involved in the translation and adaptation of the product. They are used in various contexts; for example, they might be informally used in a document published by the European Union or they might be introduced in HTML element under the lang attribute. In the case of the European Union style guide, the language codes are based on the ISO 639-1 alpha-2 code; in HTML, the language tags are generally defined within the Internet Engineering Task Force's Best Current Practice (BCP). The decision to use one type of code or tag versus another depends upon the nature of the project and any requirements set out for the localization specialist.

Most frequently, there is a primary sub-code that identifies the language (e.g., "en"), and an optional sub-code in capital letters that specifies the national variety (e.g., "GB" or "US" according to ISO 3166-1 alpha-2). The sub-codes are typically linked with a hyphen, though in some contexts it's necessary to substitute this with an underscore.

There are multiple language tag systems available for language codification. For example, the International Organization for Standardization (ISO) specifies both two- and three-letter codes to represent languages in standards ISO 639-1 and ISO 639-2, respectively. Source:[wikipedia]