As to language functions, different linguists propose their understanding of language functions. Generally they agree upon the following functions of language: 

A: The informative function is the major role of language. Language is the instrument of thought and people often feel they need to speak their thoughts aloud. The use of language as a record of facts is a prerequisite of social development. 

B: The interpersonal function is the most important sociological use of language by which people establish and maintain their status in a society. 

C. The performative function of language is primarily to change the social status of persons, as in marriage ceremonies, the sentencing of criminals, the blessing of children, the naming of sth, etc. 

D. The emotive function is one of the most powerful uses of language as it is crucial to change the emotional status of an audience for or against someone or something.

E. The phatic function refers to the fact that language helps define and maintain interpersonal relations. 

F. The recreational function refers to the fact that people use language as a tool to entertain themselves or others. 

G. The metalingual function is that language can be used to talk about itself. For example, one can sue the word “book” to talk about a book. This function makes a language infinitely self-reflexive: we human beings talk about talk and think about thinking, and thus only human can ask what a word means to communicate, to think and to be human.