A first language (also native language, mother tongue, arterial language, or L1) is the language or are the languages a person has learned from birth[1] or that a person speaks the best and so is often the basis for sociolinguistic identity[citation needed]. 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.[2] Children brought up speaking more than one language can have more than one native language, and be bilingual.