A posteriori language

A planned or constructed language (sometimes called a conlang) is a language whose phonology, grammar, and vocabulary have been consciously devised for human or human-like communication, instead of having developed naturally. It is also referred to as an artificial or invented language. There are many possible reasons to create a constructed language, such as: to ease human communication (see international auxiliary language and code), to give fiction or an associated constructed setting an added layer of realism, for experimentation in the fields of linguistics, cognitive science, and machine learning, for artistic creation, and for language games.

The expression planned language is sometimes used to mean international auxiliary languages and other languages designed for actual use in human communication. Some prefer it to the adjective artificial, for the latter may be perceived as pejorative. Outside Esperanto culture, the term language planning means the prescriptions given to a natural language to standardize it; in this regard, even "natural languages" may be artificial in some respects. Prescriptive grammars, which date to ancient times for classical languages such as Latin and Sanskrit, are rule-based codifications of natural languages, such codifications being a middle ground between naive natural selection and development of language and its explicit construction. The term glossopoeia is also used to mean language construction, particularly construction of artistic languages.

As a quantitative example of the use of conlangs within a country, the Hungarian census of 2001 found 4570 speakers of Esperanto, 10 of Romanid, 2 each of Interlingua and Ido and 1 each of Idiom Neutral and Mundolinco. The Russian census of 2010 found 992 speakers of Esperanto, 9 of Ido, 1 of Edo language and no speakers of Slovio or Interlingua.

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