Linguistics is a science. It is the scientific study of language. The term "linguistics" was first used in the mid-nineteenth century. It is an extremely broad field which encompasses grammar, phonology, and semantics. Before the mid-nineteenth century, the field was known as philology.
Comparative philologists, such as Sir William Jones (1746–1794), laid the foundation for what would become comparative historical linguistics. They discovered that Sanskrit resembles Greek and Latin in its influence on the development of languages and that languages often have a common source. (For instance, the five Romance languages are derived from Latin.)
Language acquisition theories are part of linguistics. Audiolingualism, popular in the 1950s and and 1960s, was based on behaviorism—habit formation. Accuracy, drills, and repetition are part of this teaching method. Noam Chomsky, an erudite scholar, refuted Audiolingualism. Chomsky claimed that children are born with a "universal grammar" and that habit formation is not central to language learning. As a language teacher myself, I make more use of the practical techniques of Audiolingualism than Chomsky's abstract theories.
Aspiring language teachers often study applied linguistics. This subfield is concerned with language teaching—including bilingual education in public schools.