About Mother Tongue

                    A first language also "native language", "mother tongue" or "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, there can be more than one mother tongue, when the child's parents speak different languages. Those children are usually called bilingual.
                    The general usage of the term "mother tongue" denotes not only language one learn from one's mother, but also the speaker dominant and home language, not only the first language according to the time of acquisition, but the first with regard to it's importance and the speaker's ability to master it's linguistic and communicative aspect.