Words and sentences are used to convey meanings. Linguists study this too, seeking to specify precisely what words mean, how they combine into sentence meanings, and how these combine with contextual information to convey the speaker's thoughts. The first two of these areas of investigation are called semantics , and the third is called pragmatics . Even the most formal and abstract work on linguistic structure is colored by the awareness that language is a uniquely human phenomenon. It isn't surprising, then, that linguistic research shares some concerns with just about every one of the human sciences, from psychology and neurology to literary study, anthropology, sociology, and political science.
All languages change .
In other words, languages have histories, and a complete understanding of a linguistic structure often involves examining variation and change in the language under investigation. This is extremely difficult in most cases, because the vast majority of languages have had no writing systems until very recently. Hence, most linguistic explanations focus on what speakers must know in order to speak and understand language the way all normal humans do. There are many facets to the study of language and brain . It encompasses both child language acquisition and how adults produce and process language.