Generally, when people use language to relate to or influence others, they are applying the sociological functions of language. There are basically five types of such functions: interpersonal, informative, imperative, performative, and emotive.
As for the interpersonal function of language, it is about how people use language to negotiate and/or maintain social status. In most languages, there are distinct registers, such as ritual, formal, informal, casual and intimate speech. People make use of language in different registers to help establish themselves in society and maintain relations with one another. For example, people who want to increase their power often try to imitate the speech of those in power. A speaker or writer who wants to develop greater solidarity with the audience usually attempts to use the same register that the target audience uses and appreciates. Besides, it frequently happens that language is used not to say something relevant but just to maintain a relationship, which can be well explained by the cleverly social chattering at cocktail parties.
The use of speech or writing to influence the cognitive content or state of others is the informative function of language. This function is always part of other functions. Besides, to maximize the formative function of language it should be built on the existing cognitive state of the receptor.
The imperative function of language is about the attempts to influence the behavior of receptors. This can be done through commands, exhortations and even more effectively by means of smart jokes, suitable illustrations, searching questions, etc. Its application, with lots of a verbal negotiating, implies a measure of authority or power, although its effectiveness involves the receptor’s self-interest.
The performative function of language involves a change in the status of the receptor. The speeches themselves are expected to establish a different status of an object, such as the speech used in solemnizing a marriage. Mostly, performative language is highly ritualized and fixed in form which ensures the power and prestige of such speech.
The emotive function of language involves affecting the emotive state of receptors. For this reason, it profoundly exploits the associative or connotative meanings of words. This function may be understood as the most powerful and fearful aspect of language – because the emotions that can be influenced is unlimited. Language can kindle numerous emotions, from religious devotions to hilarious laughters. This function is the object for various groups, from professional linguists to powerful politicians.
In fact, most speeches and writings involve several different functions of language and in different proportions.