What is Language ?

We are tool-using social  animals. The most powerful tool known is the one we use to build every other tool: language - spoken or written. But tools can be used with little or no skill to turn out mundane artifacts and garbage. By honing your skills with language you - yes, you - can craft masterpieces. A study of linguistics can help you acquire such skills, but be warned: the pursuit of linguistic knowledge is highly addictive.
... consider the consequences of adopting, as an understanding of education, the ability to tell rubbish from Reason. Nothing more. Nothing but the power, and the propensity, to discover that a statement is worthless, or a term without meaning, or a proposition absurd. That would also be the power to make statements that are not worthless, and propositions that make demonstrable sense.
The Gift of Fire, Richard Mitchell - (The Underground Grammarian)

Linguistics is the scientific investigation of language, a means for discovering the mechanisms of language by asking well-formulated questions and seeking answers. The first question to be answered about language is quite a simple one: what is language?

A Language is a coding system and a means by which information may be transmitted or shared between two or more communicators for purposes of command, instruction or play.

Not every coding system is a fully-featured language like human speech, yet it will have some of the features of all languages. A coding system may be artificial or natural. Computer languages are artificial languages modelled partly on human language. The 'helix of life' - DNA -  has many of the hallmarks of a language in the way that it carries codes for the production of the chemicals of life. It even has components which may be called 'words', and it has stop codes which correspond to our written punctuation.

In every transmission system there is at least one element of language. An ordinary lighthouse can be thought of in terms of language: it is part of the maritime signalling system and it conveys at least one message. The simplest message is "keep clear!", but other information can be transmitted. Where the height of the light is given on charts it allows a navigator to determine the ship's distance from the coast by use of the dipping range or a sextant.   Colour, flashing, or occulting applied to the light can be used to identify the lighthouse by name and by geographical location.

Any means by which a signal is communicated, where the signal can be received and acted on as a command, instruction, or element of play qualifies as use of language. A visual, chemical, auditory or mechanical event does not alone count as an instance of language. If the wind causes a tree to tap on your window, it isn't language. But if you see a large plant tapping on your window where there is no breeze - and you have no garden - you may need to read up about triffids.

Until about the start of the 20th century, language study was mainly concerned with grammar. Since that time, linguistics has grown many branches, and overlaps with many other disciplines. Grammar still remains a core area of study, with its components of word sounds - phonology, written word 'shapes' - morphology, letter and word sequences - syntax and the meanings behind the words - semantics.

Linguistics has had to expand its horizons because there is more to language use than just the spoken or written word. To take part fully in a conversation we need to take advantage of every clue offered as to a speaker's intended meaning. We need to understand the speaker's body language, the speaker's beliefs about what words mean and the speaker's agenda. Absent any of these and a listener may well 'get hold of the wrong end of the stick', which is a really bad idea.

Semiotics: the study of signs.

Spoken language is merely the most common form of human language, other forms are possible.  An established sign language is a true communal language independant of spoken language - it has its morphemes, words and syntax, and these are not just gestural equivalents of spoken words. But even hearing people supplement spoken language with body movements. Some gestures are conscious and some are subconscious, but alongside the gestures that we all recognise is body language. In order to fully understand someone in conversation, we must understand the gestures and body language of the community. By way of example, in England, an upwards and backwards jerk of the head with a click of the tongue in response to a question is considered rude, and may mean: "What did you say?" or "What a stupid question!".   In Iran, it is a socially normal and acceptable gesture, and simply means "no."

Hermeneutics: old world knowledge.

Hermeneutics deals with the relationship of parts of a text with the whole of a text.  We cannot understand the parts, except within the context of the whole text, but we cannot understand the whole text and thus derive its context without knowledge of the parts.  By applying various insights we can break out of this hermeneutic circle.  For example, in order to find out what Shakespeare meant by a specific word or phrase we can look at contemporary documents to see how the term was used by others in Shakespeare's day.

Pragmatics: real world knowledge.

Pragmatics deals with common knowledge.  Or rather, it deals with language users who have real-world knowledge, wants and needs.  When we write or talk, we rarely feel the need to explain all or indeed any of the physical, chemical or biological processes implied by our words.   If a child says: "I fell from a tree and hurt my leg." , it is a plausible statement.  It is plausible to the hearer because we humans tend to share our experiences, either by word of mouth or by attempted defiance of gravity.  Evolution teaches us that learning by word of mouth tends to be more survivable.  Unless we are inhumanly antisocial, we take the child's statement of injury as a request for assistance, an expression of a need.  There is nothing in the grammar of English that identifies the statement as a request, but we pragmatic humans still manage to understand the intent behind the words.

Philosophy: the pursuit of knowledge.

A study of philosophy is not essential to a study of linguistics.  However, if not pursued to excess it can give insights into how the mind works.  Human language may be viewed as a means by which an idea in one mind can be transmitted with minimal distortion into another mind.   Philosophy - especially in its historical shifts -  is a useful tool for helping to understand how the mind works.  Please note: mind, not brain.

Psychology: language as behaviour.

The function of the brain as regards language acquisition and use is a major area in its own right: cognitive science.   But that must remain a subject for another article.  For general linguistic purposes it is enough to learn something about the psychology of how language interfaces with emotion.  Rather than make this article overlong by talking about emotions, I shall attempt, by way of demonstrating my point, to stir some up:
    A Drop In The Ocean

     A breeze on the ocean,
       a star in the sky,
    a sea in slow motion,
      a shadowing sky.

    A silence, so moving,
      a too swifting hour,
   an all too brief kiss,
     a single red flower.

    Two hands, gently parting,
      two people, one sigh,
   a too empty harbour,
     a  glistening eye.

   A drop in the ocean,
     a  ship on the deep,
   a stifled emotion,
     a man does not weep.

Recommended reading:
The Rhetoric of Richard Mitchell: Is Literacy a Moral Condition? Free pdf
Some full texts on General philosophy

If you enjoyed reading this article, or if you are keen to know more about how language works, these links to some of my related articles may interest you:
A mother's influence on language
How babies learn language
A brief history of the English language - not that brief, there are 6 parts!
Did language invent humans?
The hermeneutic circle.
Digging Beneath the Surface of Grammar
A Grammar of Questions.

John Searle' Chinese Room Argument:
Thinking Machines and The Semantic Quagmire
The Intelligence in the Chinese Room.

Ambiguity in language:
Strangeness And Ambiguity In Language
Random Reward Schedules and the Ambiguity of Language.