First language

First language, native language or mother tongue is the language a person learns first. Correspondingly, the person is called a native speaker of the language, although one may also be a native speaker of more than one language, if all of the languages are learned naturally without formal instruction, such as through cultural immersion before puberty. Often a child learns the basics of his or her first languages from his or her family.

Good skills in one's native languages are essential for further learning, as a native language is thought to be a base of thinking. Incomplete first language skills often make learning other languages difficult. Native language has therefore a central role in education.

The term "mother tongue" should not be interpreted to mean that it is the language of one's mother. In some paternal societies, the wife moves in with the husband and thus may have a different first language, or dialect, than the local language of the husband. Yet their children usually only speak their local language. Only a few will learn to speak their mothers' languages like natives. Mother in this context probably originated from the definition of mother as source, or origin; as in mother-country or land.

One can have two or more native languages, thus being a native bilingual or indeed multilingual. The order in which these languages are learned is not necessarily the order of proficiency. For instance, a French-speaking couple might have a daughter who learned French first, then English; but if she grew up in the United States, she is likely to become more proficient in English.

The Brazilian linguist Cleo Altenhofen considers the denomination "mother tongue" in its general usage to be imprecise and subject to various interpretations that are biased in linguistic prejudices, especially with respect to bilingual children from ethnic minority groups. He cites his own experience as a bilingual speaker of Portuguese language and Riograndenser Hunsrückisch, a German-rooted language brought to Southern Brazil by the first German immigrants. In his case, like that of many children whose home language differs from the language of the environment (the 'official' language), it is debatable which language is his 'mother tongue'. Many scholars gave definitions of 'mother tongue' through the years based on common usage, the emotional relation from the speaker towards the language, and even its dominance in relation to the environment. However, all of these criteria lack precision.

Definitions
reference:
 * Definition based on Origin: the language(s) one learned first (the language(s) in which one has established the first long-lasting verbal contacts).
 * Definition based on internal identification: the language(s) one identifies with/as a native speaker of;
 * Definition based on external indentification: the language(s) one is identified with/as a native speaker of, by others.
 * Definition based on competence: the language(s) one knows best.
 * Definition based on function: the language(s) one uses most.