information:extraction
Usage and meaning

When studying the way in which words and signs are used, it is often the case that words have different meanings, depending on the social context of use. An important example of this is the process called deixis, which describes the way in which certain words refer to entities through their relation between a specific point in time and space when the word is uttered. Such words are, for example, the word, "I" (which designates the person speaking), "now" (which designates the moment of speaking), and "here" (which designates the position of speaking). Signs also change their meanings over time, as the conventions governing their usage gradually change. The study of how the meaning of linguistic expressions changes depending on context is called pragmatics. Deixis is an important part of the way that we use language to point out entities in the world. Pragmatics is concerned with the ways in which language use is patterned and how these patterns contribute to meaning. For example, in all languages, linguistic expressions can be used not just to transmit information, but to perform actions. Certain actions are made only through language, but nonetheless have tangible effects, e.g. the act of "naming", which creates a new name for some entity, or the act of "pronouncing someone man and wife", which creates a social contract of marriage. These types of acts are called speech acts, although they can also be carried out through writing or hand signing.

The form of linguistic expression often does not correspond to the meaning that it actually has in a social context. For example, if at a dinner table a person asks, "Can you reach the salt?", that is, in fact, not a question about the length of the arms of the one being addressed, but a request to pass the salt across the table. This meaning is implied by the context in which it is spoken; these kinds of effects of meaning are called conversational implicatures. These social rules for which ways of using language are considered appropriate in certain situations and how utterances are to be understood in relation to their context vary between communities, and learning them is a large part of acquiring communicative competence in a language.