A language is a dynamic set of sensory symbols of communication and the elements used to manipulate them. Language can also refer to the use of such systems as a general phenomenon. Strictly speaking, language is considered to be an exclusively human mode of communication. Although other animals make use of quite sophisticated communicative systems, 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 Western Philosophy, 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. More commonly though, the English word "language", derived ultimately from lingua, Latin for tongue, typically refers only to expressions of reason which can be understood by other people, most obviously by speaking.

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.
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, there is nothing about the Spanish word nada itself that forces Spanish speakers to convey the idea of "nothing". Another set of sounds (for example, the English word nothing) could equally be used to represent the same concept, but all Spanish speakers have acquired or learned to correlate this meaning for this particular sound pattern. For Slovenian, Croatian, Serbian or Bosnian speakers on the other hand, nada means something else; it means "hope".

This arbitrariness even applies to words with an onomatopoetic dimension (i.e. words that to some extent simulate the sound of the token referred to). For example, several animal names (e.g. cuckoo, whip-poor-will, katydid) are derived from sounds the respective animal makes, but these forms did not have to be chosen for these meanings. Non-onomatopoetic words can stand just as easily for the same meaning. For instance, the katydid is called a "bush cricket" in British English, a term that bears no relation to the sound the animal makes. In time, onomatopoetic words can also change in form, losing their mimetic status. Onomatopoetic words may have an inherent relation to their referent, but this meaning is not inherent, thus they do not violate arbitrariness.


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.

The historical record of linguistics begins in India with Pāṇini, the 5th century BCE grammarian who formulated 3,959 rules of Sanskrit morphology, known as the Aṣṭādhyāyī (अष्टाध्यायी) and with Tolkāppiyar, the 3rd century BCE[dubious – discuss] grammarian of the Tamil work Tolkāppiyam(தொல்காப்பியம்). Pāṇini’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. Tolkāppiyar'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 (سیبویه) made a detailed and professional description of Arabic in 760 CE in his monumental work, Al-kitab fi al-nahw (الكتاب في النحو, 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, which are characterized as being highly systematic.


Some languages, most constructed, are meant specifically for communication between people of different nationalities or language groups as an easy-to-learn second language. Several of these languages have been constructed by individuals or groups. Natural, pre-existing languages may also be used in this way - their developers merely catalogued and standardized their vocabulary and identified their grammatical rules. These languages are called naturalistic. One such language, Latino Sine Flexione, is a simplified form of Latin. Two others, Occidental and Novial, were drawn from several Western languages.

To date, the most successful auxiliary language is Esperanto, invented by Polish ophthalmologist Zamenhof. It has a relatively large community roughly estimated at about 2 million speakers worldwide, with a large body of literature, songs, and is the only known constructed language to have native speakers, such as the Hungarian-born American businessman George Soros. Other auxiliary languages with a relatively large number of speakers and literature are Interlingua and Ido.

Controlled natural languages are subsets of natural languages whose grammars and dictionaries have been restricted in order to reduce or eliminate both ambiguity and complexity. The purpose behind the development and implementation of a controlled natural language typically is to aid non-native speakers of a natural language in understanding it, or to ease computer processing of a natural language. An example of a widely used controlled natural language is Simplified English, which was originally developed for aerospace industry maintenance manuals.

Mathematics and computer science use artificial entities called formal languages (including programming languages and markup languages, and some that are more theoretical in nature). These often take the form of character strings, produced by a combination of formal grammar and semantics of arbitrary complexity.

A programming language is an extreme case of a formal language that can be used to control the behavior of a machine, particularly a computer, to perform specific tasks. Programming languages are defined using syntactic and semantic rules, to determine structure and meaning respectively.
Programming languages are used to facilitate communication about the task of organizing and manipulating information, and to express algorithms precisely. Some authors restrict the term "programming language" to those languages that can express all possible algorithms; sometimes the term "computer language" is used for artificial languages that are more limited.

The term "animal languages" is often used for non-human languages. Linguists do not consider these to be "language", but describe them as animal communication, because the interaction between animals in such communication is fundamentally different in its underlying principles from human language. Nevertheless, some scholars have tried to disprove this mainstream premise through experiments on training chimpanzees to talk. Karl von Frisch received the Nobel Prize in 1973 for his proof of the language and dialects of the bees. Current research indicates that signalling codes are the most fundamental precondition for every coordination within and between cells, tissues, organs and organisms of all organismic kingdoms. All of these signalling codes follow combinatorial (syntactic), context-sensitive (pragmatic) and content-specific (semantic) rules. In contrast to linguists, biolinguistics and biosemiotics consider these codes to be real languages.

In several publicized instances, non-human animals have been taught to understand certain features of human language. Chimpanzees, gorillas, and orangutans have been taught hand signs based on American Sign Language. The African Grey Parrot, which possesses the ability to mimic human speech with a high degree of accuracy, is suspected of having sufficient intelligence to comprehend some of the speech it mimics. Most species of parrot, despite expert mimicry, are believed to have no linguistic comprehension at all.

While proponents of animal communication systems have debated levels of semantics, these systems have not been found to have anything approaching human language syntax.