Mother Tounge

         A first language also native language, mother tongue, arterial language is the language a person has learned from birth or within the critical period, or that a person speaks the best and so is often the basis for sociolinguistic identity. In some countries, the terms native language or mother tongue refer to the language of one's ethnic group rather than one's first language.
      Sometimes the term mother tongue or mother language is used for the language that a person learnt as a child at home (usually from their parents). Children growing up in bilingual homes can, according to this definition, have more than one mother tongue or native language.
        It is quite possible that the first language learned is no longer a speaker's dominant language. This includes young immigrant children, whose families have moved to a new linguistic environment, as well as people who learned their mother tongue as a young child at home (rather than the language of the majority of the community), who may have lost, in part or in totality, the language they first acquired.