A language is a system for encoding and decoding information. In its most common use, the term refers to so-called "natural languages" — the forms of communication considered peculiar to humankind. In linguistics the term is extended to refer to the human cognitive facility of creating and using language. Essential to both meanings is the systematic creation and usage of systems of symbols—each referring to linguistic concepts with semantic or logical or otherwise expressive meanings. The most obvious manifestations are spoken languages such as English or Spoken Chinese. However, there are also written languages and other systems of visual symbols such as sign languages. Although some other animals make use of quite sophisticated communicative systems, and these are sometimes casually referred to as animal language, none of these are known to make use of all of the properties that linguists use to define language in the strict sense. When discussed more technically as a general phenomenon then, "language" always implies a particular type of human thought which can be present even when communication is not the result, and this way of thinking is also sometimes treated as indistinguishable from language itself. In Western Philosophy for example, language has long been closely associated with reason, which is also a uniquely human way of using symbols. In Ancient Greek philosophical terminology, the same word, logos, was used as a term for both language or speech and reason, and the philosopher Thomas Hobbes used the English word "speech" so that it similarly could refer to reason, as will be discussed below. Properties of language A set of commonly accepted signs (indices, icons or symbols) is only one feature of language; all languages must define (i) the structural relationships between these signs in a system of grammar, (ii) the context wherein the signs are used (pragmatics) and (iii) dependent on their context the content specifity, i.e. its meaning (semantics). Rules of grammar are one of the characteristics sometimes said to distinguish language from other forms of communication. They allow a finite set of signs to be manipulated to create a potentially infinite number of grammatical utterances. However, this definition is self-circular. The structural relationships make sense only within language, the structure of language exists only in language. It is impossible to have a logically correct definition of a noun or verb. And logic itself concerns itself with propositions which are closely linked with content specificity i.e. semantics. Another property of language is that its symbols are arbitrary. Any concept or grammatical rule can be mapped onto a symbol. In other words, most languages make use of sound, but the combinations of sounds used do not have any necessary and inherent meaning – they are merely an agreed-upon convention to represent a certain thing by users of that language. For instance, the sound combination nada carries the meaning of "nothing" in the Spanish language and also the meaning "thread" in the Hindi language. There is nothing about the word nada itself that forces Hindi speakers to convey the idea of "thread", or the idea of "nothing" for Spanish speakers. Other sets of sounds (for example, the English words nothing and thread) could equally be used to represent the same concepts, but all Spanish and Hindi speakers have acquired or learned to correlate their own meanings for this particular sound pattern. Indeed, for speakers of Slovenian and other South Slavic languages, the sound combination carries the meaning of "hope", while in Indonesian, it means "tone". Origin of language Ancient Tamil inscription at the Brihadeeswara Temple in Thanjavur Main article: Origin of language Even before the theory of evolution made discussion of more animal-like human ancestors commonplace, philosophical and scientific speculation casting doubt on the use of early language has been frequent throughout history. In modern Western Philosophy, speculation by authors such as Thomas Hobbes and later Jean-Jacques Rousseau led to the Académie française declaring the subject off-limits.[citation needed] The origin of language is of great interest to philosophers because language is such an essential characteristic of human life. In classical Greek philosophy such inquiry was approached by considering the nature of things, in this case human nature. Aristotle, for example, treated humans as creatures with reason and language by their intrinsic nature, related to their natural propensities to be "political," and dwell in city-state communities (Greek: poleis)[1]. The study of language Linguistics Main article: Linguistics Linguistics is the scientific study of language, encompassing a number of sub-fields. At the core of theoretical linguistics are the study of language structure (grammar) and the study of meaning (semantics). The first of these 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. Theoretical linguistics is mostly concerned with developing models of linguistic knowledge. The fields that are generally considered as the core of theoretical linguistics are syntax, phonology, morphology, and semantics. Applied linguistics attempts to put linguistic theories into practice through areas like translation, stylistics, literary criticism and theory, discourse analysis, speech therapy, speech pathology and foreign language teaching. History Main article: History of linguistics The historical record of linguistics begins in India with Pa?ini, the 5th century BCE grammarian who formulated 3,959 rules of Sanskrit morphology, known as the A??adhyayi and with Tolkappiyar, the 2nd century BCE grammarian of the Tamil work Tolkappiyam.[9] Pa?ini’s grammar is highly systematized and technical. Inherent in its analytic approach are the concepts of the phoneme, the morpheme, and the root; Western linguists only recognized the phoneme some two millennia later.[citation needed] Tolkappiyar's work is perhaps the first to describe articulatory phonetics for a language. Its classification of the alphabet into consonants and vowels, and elements like nouns, verbs, vowels, and consonants, which he put into classes, were also breakthroughs at the time. In the Middle East, the Persian linguist Sibawayh made a detailed and professional description of Arabic in 760 CE in his monumental work, Al-kitab fi al-nahw (The Book on Grammar), bringing many linguistic aspects of language to light. In his book, he distinguished phonetics from phonology. Later in the West, the success of science, mathematics, and other formal systems in the 20th century led many to attempt a formalization of the study of language as a "semantic code". This resulted in the academic discipline of linguistics, the founding of which is attributed to Ferdinand de Saussure.[citation needed] In the 20th century, substantial contributions to the understanding of language came from Ferdinand de Saussure, Hjelmslev, Émile Benveniste and Roman Jakobson,[10] which are characterized as being highly systematic.[10] Study of language *Linguistics *Historical linguistics *Synchronic analysis *Philology *Philosophy of language *Universal grammar Types of language and language relationships *Dialect *Language family *Extinct language *Word game Non-spoken forms of communication *Written language *Sign language *Whistled language *Drum languages *Non-verbal communication Origins of language *Origin of language *Evolutionary linguistics *Biolinguistics *FOXP2 - gene implicated in cases of specific language impairment (SLI) Religion and mythology *Adamic language Education and public policy *Language education *Language school *Language policy *Language reform *Linguistic protectionism *Official language Language and culture *Linguistic relativity - (Sapir-Whorf Hypothesis) Communication with other species *Great ape language Semiotics *Symbolic communication *Symbolic linguistic representation *Metacommunicative competence Other *Translation *Second language *Phonetic transcription *Dyslexia *ISO 639 - 2- and 3-letter ID codes for languages