A language is not only studied from the internal viewpoint but also from the external one. Internally, it is studied based on its internal structures; whereas, externally, it is based on the linguistic factors in relation to the factors beyond the language. A study of internal language structures (or, it is based on the sub-systems of a language) will result sub-discipline of linguistics such as phonetics, phonology, morphology, syntax and semantics. It is conducted through theories and procedures belonging to the discipline of linguistics; it is not related to the problems beyond the language.