Mother tongue 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. Sometimes, there can be more than one mother tongue, when the child's parents speak different languages. Mother tongue of a child is part of their personal, social and cultural identity. Another impact of the first language is that it brings about the reflection and learning of successful social patterns of acting and speaking. It is basically responsible for differentiating the linguistic competence of acting.
Sometimes the term native language is used to indicate a language that a person is as proficient in as a native individual of that language's "base country", or as proficient as the average person who speaks no other language but that language. Sometimes the term mother tongue or mother language is used for the language that a person learned as a child at home. Children growing up in bilingual homes can, according to this definition, have more than one mother tongue or native language.
To a person his mother tongue is a “blessing in disguise”. It is not merely a time-table subject in his education but is forced upon him from all sides. It is learned by both the direct or conscious and the indirect or unconscious method. The mother tongue is an indispensable instrument for the development of the intellectual, moral and physical aspects of education. It is a subject thought and by which other subjects can be tackled, understood and communicated.