**Linguistics** is the study of language. People who study language are called linguists.

There are five main parts of linguistics: the study of sounds (phonology), the study of parts of words, like "un-" and "-ing" (morphology), the study of word order and how sentences are made (syntax), the study of the meaning of words (semantics), and the study of the unspoken meaning of speech that is separate from the literal meaning of what is said (for example, saying "I'm cold" to get someone to turn off the fan (pragmatics). 

There are many ways to use linguistics every day. Some linguists are theoretical linguists and study the theory and ideas behind language, such as historical linguistics (the study of the history of language, and how it has changed), or the study of how different groups of people may use language differently (sociolinguistics). Some linguists are applied linguists and use linguistics to do things. For example, forensic linguistics is used in crime investigations, and computational linguistics is used to help make computers understand languages, as in speech recognition.

Specialties
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There are many different specialties (subfields or sub-disciplines) within linguistics. 

Theoretical linguistics looks at how languages are structured and how they work. This includes phonology, morphology, syntax, semantics, and pragmatics. 

Evolutionary linguistics explores the origins of language as a whole. Historical linguistics studies how languages change over time, and how languages were used in the past. This includes etymology, the study of the history of words. Comparative linguistics compares different languages to find similarities between them. That makes it possible to find things shared by all the languages of the world, and to learn the languages that are related in a language family. 

Cognitive linguistics looks at how language and thoughts are organised in the human brain. This includes psycholinguistics, which explores the representation and function of language in the mind; and neurolinguistics, which looks at language processing in the brain. 

Language acquisition looks at how humans recognize and understand language. First language acquisition explores how children acquire (learn) their first language; second language acquisition explores how adults learn languages. 

Some sub-disciplines of linguistics focus on understanding how languages are used in society or in the world. Sociolinguistics studies how language is used in society; for example, how factors such as gender and social class can impact how language is used. Discourse analysis is the study of entire conversations or texts. 

Although linguistics is the scientific study of language, many other intellectual disciplines are relevant to language and overlap with it. For example, semiotics is the general study of signs and symbols both within language and outside it. Literary theorists study the use of language in literature. Linguistics additionally draws on and informs work from fields such as acoustics, anthropology, biology, computer science, human anatomy, informatics, neuroscience, philosophy, psychology, sociology, and speech-language pathology.

History
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The study of language began in India with Pāṇini, the 5th century BC grammarian who wrote about the 3,959 rules of Sanskrit grammar, which described the different kinds of vowels and consonants of Sanskrit as well as its verb and noun classes. In the Middle East, Sibawayh (سیبویه) wrote a book about Arabic in 760 AD, *Al-kitab fi al-nahw* (الكتاب في النحو, *The Book on Grammar*) and was the first known author to talk about the difference between sounds and phonemes.

Linguistics started in the West as early as it did in the East, but Western linguistics at that time was more like philosophy and less the study of language. Plato was the first western philosopher to write about semantics in his *Cratylus* in which he argues that words represent concepts that are eternal and exist in the world of ideas[*source?*]. The word *etymology* is first used to talk about the history behind a word's meaning.

For many centuries most linguistic work was "philology".