||This article needs additional citations for verification. (April 2013)|
Theoretical linguistics is the branch of linguistics that is most concerned with developing models of linguistic knowledge. The fields that are generally considered the core of theoretical linguistics are syntax, phonology, morphology, and semantics. Although phonetics often informs phonology, it is often excluded from the purview of theoretical linguistics, along with psycholinguistics and sociolinguistics. Theoretical linguistics also involves the search for an explanation of linguistic universals, that is, properties all languages have in common.
Major fields 
|This section requires expansion. (May 2008)|
Phonetics is the study of speech sounds with concentration on three main points :
- Articulation : the production of speech sounds in human speech organs.
- Perception : the way human ears respond to speech signals, how the human brain analyses them.
- Acoustic features : physical characteristics of speech sounds such as color, loudness, amplitude, frequency etc.
According to this definition, phonetics can also be called linguistic analysis of human speech at the surface level. That is one obvious difference from phonology, which concerns the structure and organisation of speech sounds in natural languages, and furthermore has a theoretical and abstract nature. One example can be made to illustrate this distinction: In English, the suffix -s can represent either /s/, /z/, or can be silent (written Ø) depending on context.
Orthographic representation : S, s Phonetic features: Phonetic representations: [s], [z], Ø Perception through the ear: high frequency sounds accompanied by a hissing noise. Acoustic features: Frequency : 8000 – 11000 Hz Color : similar to the hissing noise made by snakes. Phonological characteristics : Occurrence : beginning, middle or end of words. Accompanied by vowels or consonants. Distinguishes meanings of words depending on context: s''low ≠ g''low
Articulatory phonetics 
The field of articulatory phonetics is a subfield of phonetics. In studying articulation, phoneticians attempt to document how humans produce speech sounds (vowels and consonants). That is, articulatory phoneticians are interested in how the different structures of the vocal tract, called the articulators (tongue, lips, jaw, palate, teeth etc.), interact to create the specific sounds.
Auditory phonetics 
Auditory phonetics is a branch of phonetics concerned with the hearing, acquisition and comprehension of phonetic sounds of words of a language. As articulatory phonetics explores the methods of sound production, auditory phonetics explores the methods of reception—the ear to the brain, and those processes.
Acoustic phonetics 
Acoustic phonetics is a subfield of phonetics which deals with acoustic aspects of speech sounds. Acoustic phonetics investigates properties like the mean squared amplitude of a waveform, its duration, its fundamental frequency, or other properties of its frequency spectrum, and the relationship of these properties to other branches of phonetics (e.g. articulatory or auditory phonetics), and to abstract linguistic concepts like phones, phrases, or utterances.
Phonology is the study of language sounds. Phonology is divided into two separate studies, phonetics and phonemics. Phonetics is what depicts the sounds we hear. It calls attention to the smallest details in language sounds. There are three kinds of phonetics: acoustic phonetics, auditory phonetics, and articulatory phonetics. Acoustic phonetics deals with the physical properties of sound, what sounds exactly are coming from the person speaking. Auditory phonetics deals with how the sounds are perceived, exactly what the person hearing the sounds is perceiving. Finally, articulatory phonetics studies how the speech sounds are produced. This is what describes the actual sounds in detail. It is also known as descriptive phonetics.
Phonemics studies how the sounds are used. It analyzes the way sounds are arranged in languages and helps you to hear what sounds are important in a language. The unit of analysis for phonemics is called phonemes. "A phoneme is a sound that functions to distinguish one word from another in a language." For example, the English word 'tie' sounds different from the word 'die': the sounds that differentiate the words are [t] and [d].
Morphology is the study of word structure. For example, in the sentences The dog runs and The dogs run, the word forms runs and dogs have an affix -s added, distinguishing them from the base forms dog and run. Adding this suffix to a nominal stem gives plural forms, adding it to verbal stems restricts the subject to third person singular. Some morphological theories operate with two distinct suffixes -s, called allomorphs of the morphemes Plural and Third person singular, respectively. Languages differ with respect to their morphological structure. Along one axis, we may distinguish analytic languages, with few or no affixes or other morphological processes from synthetic languages with many affixes. Along another axis, we may distinguish agglutinative languages, where affixes express one grammatical property each, and are added neatly one after another, from fusional languages, with non-concatenative morphological processes (infixation, umlaut, ablaut, etc.) and/or with less clear-cut affix boundaries.
Syntax is the study of language structure and phrasal hierarchies, depicted in parse tree format. It is concerned with the relationship between units at the level of words or morphology. Syntax seeks to delineate exactly all and only those sentences which make up a given language, using native speaker intuition. Syntax seeks to describe formally exactly how structural relations between elements (lexical items/words and operators) in a sentence contribute to its interpretation. Syntax uses principles of formal logic and Set Theory to formalize and represent accurately the hierarchical relationship between elements in a sentence. Abstract syntax trees are often used to illustrate the hierarchical structures that are posited. Thus, in active declarative sentences in English the subject is followed by the main verb which in turn is followed by the object (SVO). This order of elements is crucial to its correct interpretation and it is exactly this which syntacticians try to capture. They argue that there must be a formal computational component contained within the language faculty of normal speakers of a language and seek to describe it.
Semantics is the study of intension, that is, the intrinsic meanings of words and phrases. Much of the work in the field of philosophy of language is concerned with the relation between meanings and the world, and this concern cross-cuts formal semantics in several ways. For example, both philosophers of language and semanticists make use of propositional, predicate and modal logics to express their ideas about word meaning; what Frege termed 'sense'.
See also 
- Ottenheimer, H.J. (2006). The Anthropology of Language: An Introduction to Linguistic Anthropology.Canada: Thomas Wadsworth.
- Ottenheimer, 34
- Ottenheimer, 36-37
- Ottenheimer, 46-47
- Ottenheimer, 47