According to Roman Jakobson in "Closing Statement: Linguistics and Poetics" (1960), language has the following six functions:

referential: this is the most obvious function of language, when you use words to indicate things or facts.
On E2, factual writeups use the referential function of language.

emotive: this is when you don't speak to convey an information, but to express your feelings. Then you communicate for yourself more than for the people who may (or may not) hear you.
On E2, Day Logs use this function almost exclusively.

conative: you try to make other people do something. This includes orders and prayers.
The Everything University is a fine example of conative speaking. Node What You Know!

phatic: this little-known function of language consists in saying something only to maintain the contact with the person you are speaking to. When you say "hello" on the phone or discuss about the weather with your hairdresser, you are using the phatic function of language. Your purpose is primarily to maintain the communication.
The all is quiet... message displayed in the Chatterbox when nobody is speaking could be considered as a phatic message, because maybe the Chatterbox would die if nobody said anything for too long...

metalingual: when language is used to speak about language, for example in a grammar or a dictionary.
The nodes about language are metalingual. This node is metalingual. This paragraph is metametalingual.

poetic: when the speaker focuses on the message for its own sake. This functions encompasses more than poetry. For example, euphony is an application of this function. You use the poetic function of language when you say "Abbott and Costello" instead of "Costello and Abbott", which has the same meaning. Georges Perec also used that function whe he wrote La Disparition (A Void) without the letter e.
The poetic function has so many aspects that it is probably present everywhere in E2. Even in nodes about poetry.

The theory behind that list establishes that saying something to someone involves the following mechanism:

An Addresser sends a Message to an Addressee.

The Message cannot be understood outside of a Context.

The Addresser and the Addresse need to understand the Code that explicits the relationship between the Message and the Context.

A physical Contact must be established between them to convey the Message.

According to Jakobson, "each of these six features (Addresser-Message-Context-Contact-Code-Addressee) determines a different function of language." Which feature corresponds to each function is left as an exercise to the reader. If my description of the function is not too obscure, it should be easy.

Jakobson's essay is described at many places on the Internet. A good place is

Log in or register to write something here or to contact authors.