Linguistics is the scientific study of language, which can be theoretical or applied. Someone who engages in this study is called a linguist.
Theoretical (or general) linguistics encompasses a number of sub-fields, such as the study of language structure (grammar) and meaning (semantics). The study of grammar encompasses morphology (formation and alteration) of words and syntax (the rules that determine the way words combine into phrases and sentences). Also a part of this field are phonology, the study of sound systems and abstract sound units, and phonetics, which is concerned with the actual properties of speech sounds (phones), non-speech sounds, and how they are produced and perceived.Linguistics compares languages (comparative linguistics) and explores their histories, in order to find universal properties of language and to account for its development and origins (historical linguistics).
Applied linguistics puts linguistic theories into practice in areas such as foreign language teaching, speech therapy, translation and speech pathology.