The functions of language

"Language is used for more than one purpose. The man who hits his thumb-nail with a hammer and utters a string of curses is using language for an expressive purpose: he is relieving his feelings, and needs no audience but himself. People can often be heard playing with language: children especially like using language as if it were a toy, repeating, distorting, inveniting, punning, jingling, and there is a play element in the use of language in some literature. But when philosophers use language to clarify their ideas on a subject, they are using it as an instrument of thought. When two neighbours gossip over the fence, or exchange conentional greetings as they pass one another in the street, language is being used to strengthen the bonds of cohesion between the members of a society. Language, it seems, is a multi-purpose instrument. One function, however, is basic: language enables us to influence one another's behaviour, and to influence it in great deatil, and thereby makes human co-operation possible. Other animals co-operate, for example many primates, and social insects like bees and ants, and use communication systems in the process. But human co-operation would be unthinkable without language, and itis obviously this function which as made language so successful and so important; other functions can be looked on as by-products. A language, of course, always belongs to a group of people, not to an individual."

-- from _The English Language: A Historical Introduction_ (2000) by Charles Barber.