1 Introduction of LanguageLanguage is a system of arbitrary vocal symbols used for human communication. The beginning of human society is communication, and the bridge of human communication is language. So, it is necessary to have a study on language.1.1 What is Language?If we check the Websters New World Dictionary , we can find several senses of “language”, 1 (a) human speech; (b) the ability to communicate by this means; (c) a system of vocal sounds and combinations of such sounds to which meaning is attributed, used for the expression or communication of thoughts and feelings; 2 (a) any means of expressing or communicating, as gestures, signs, or animal sounds; (b) a special set of symbols, letters, numerals, rules etc. used for the transmission of information, as in a computer; .(p.759) Though we use the word in its various senses, we focus on its primary sense. And the barest definition of “language” is: language is a means of verbal communication.1.2 The Functions of LanguageLanguage can not exist without the society, and the society can not break away from language. Language has a very big use in establishing and developing of human society. Language is used for communication, incarnate one s mind, and many other functions, but the main usage is communication.In general, there are seven functions of language: (1) informative, (2) interpersonal, (3) performative, (4) emotive function, (5) phatic communion, (6) recreational function, (7) metalingual function.These functions of language are in the abstract sense, that is, not in terms of using language to chat, to think, to buy and sell, to read and write, to greet, praise and condemn people, etc. And then I will explain these functions in details.1.2.1 Informative FunctionFor most people, the informative function is predominantly the major role of language. Language is the instrument of thought and people often feel need to speak their thoughts aloud, for instance, when they are working on a math problem. The use of language to record the facts is a prerequisite of social development. This is indeed a crucial function of language. It is also called ideational functional grammar. Halliday notes that “Language serves for the expression of content: that is, of the speakers experience of the real world, including the inner world of his own consciousness. In serving this function, language also gives structure to experience, and helps to determine our way of looking at things, so that it requires some intellectual effort to see them in any other way than that which our language suggests to us” (in lyons, 1970).1.2.2 Interpersonal FunctionBy far the most important sociological use of language is the interpersonal function, by which people establish and maintain their status in a society. In the framework of functional grammar, this function is concerned with interaction between the addresser and addressee in the discourse situation and the addressers attitude toward what he speaks or writes about. For example, the ways in which people address others and refer to themselves (e.g. Dear Sir, Dear Professor, yours) indicate the various grades of interpersonal relations. “Language serves to establish and maintain social rules, which include the communication roles created by language itself for example the roles of questioner and respondent, which we take on by asking or answering a question; . Through this function, . social groups are delimited, and the individual is identified and reinforced, since by enabling him to interact with others language also serves in the expression and development of his own personality .” (Halliday, in Lyons, 1970). Attached to the interpersonal function of language is its function of expressing identity. The interpersonal function is such a broad category that it is often discussed under various other terms as in the following performative, emotive, expressive and phatic function of language. They seem to emphasize different aspects of the interpersonal function.1.2.3 Performative FunctionThis concept originates from the philosophical study of language represented by Austin and Searle, whose theory now forms the back-bone of pragmatics. The performative function of language is primarily to change the social status of persons, and this kind of language employed in performative verbal acts is usually quite formal and even ritualized. The performative function can extend to the control of reality as on some magical or religious occasions. For example, in Chinese when someone breaks a bowl or a plate the host or the people present are likely to say sui sui ping an (every year be safe and happy) as a means of controlling the invisible forces which the believers feel might affect their lives adversely.1.2.4 Emotive FunctionAccording to some investigations, though the conveying of information occurs in most uses of language, it probably represents not more than 20 percent of what takes p