Linguistics is the scientific study of language, encompassing a number of sub-fields. An important topical division is between the study of language structure (grammar) and the study of meaning (semantics). Grammar encompasses morphology (the formation and composition of words), syntax (the rules that determine how words combine into phrases and sentences) and phonology (the study of sound systems and abstract sound units). Phonetics is a related branch of linguistics concerned with the actual properties of speech sounds (phones), non-speech sounds, and how they are produced and perceived.
Modern linguistics is structuralism in the sense that it "treats language as an interwoven structure, in which every item acquires identity and validity only in relation to the other items in the system." Over the twentieth century, following the work of Noam Chomsky, linguistics came to be dominated by the Generativist school, which is chiefly concerned with explaining how human beings acquire language and the biological constraints on this acquisition; generative theory is modularity in character. While this remains the dominant paradigm, other linguistic theories have increasingly gained in popularity — cognitive linguistics being a prominent example. There are many sub-fields in linguistics, which may or may not be dominated by a particular theoretical approach: evolutionary linguistics, for example, attempts to account for the origins of language; historical linguistics explores language change; and sociolinguistics looks at the relation between linguistic variation and social structures.
A variety of intellectual disciplines are relevant to the study of language. Although certain linguists have downplayed the relevance of some other fields linguistics — like other sciences — is highly interdisciplinary and draws on work from such fields as informatics, computer science, philosophy, biology, neuroscience, sociology, music, history, and anthropology.