is the method of human communication, either spoken or written, consisting of the use of words in a structured and conventional way
is a system that consists of the development, acquisition, maintenance and use of complex systems of communication, particularly the human ability to do so; and a language is any specific example of such a system. The scientific study of language is called linguistics

Language - Classifications

living language - alanguage which is still spoken in the contemporary period
dead language - a language which is still in use but is no longer the native language of any community
extinct language - a language that no longer has any speakers, especially if the language has no living descendants
endangered language or moribund language - a living language that is at risk of becoming a dead or even extinct language
attested languages - are languages (living or dead) that have been documented and for which the evidence (attestation) has survived to the present day. Evidence may be recordings, transcriptions, literature or inscriptions
unattested languages - purported languages with no direct evidence
proto-language - can be thought of as a mother language being the root which all languages in the family stem from. see philology

／var／log marcus chiu