Discourse, text and the notion of texture

The aim of the DISCOURSE ANALYSIS is to analyse the way texts work across the boundaries of single sentences or utterances to form whole stretches of language (rather than a collection of unrelated sentences).
The word TEXT and DISCOURSE mean different things. To understand what is actually meant by the term DISCOURSE, Renkema and Carter suggest considering its etymology. The basic meaning of discourse in modern ordinary usage is talk. Originally, the term came from the Medieval Latin term discurrere (meaning to circulate or to run on). It has been more frequently used to refer to prepared forms of spoken language such as speeches, where people run on about a topic, than to spontaneous talk. The modern meaning of discourse has evolved to encompass casual conversations, which just like formal speeches, run from one person to another: speakers make an effort to give their interactions shape and connectedness, as an integral part of co-operating with another speaker to create meaning. A useful metaphor to understand the term 'discourse' is that of weaving (tessitura), whereby speakers can be seen tomwork together in the same way as weavers that work together to create a pattern in some fabric (the weaving metaphor is used in some expressions such as 'losing the thread of conversation'). The term discourse is now used also for written texts, in fact also written language runs on.
The word TEXT, coming from the Latin term texere, originally meant 'something that is woven' and we can see a close relationship between text, textile (capable of being woven) and texture (having the qualify of woven cloth). The notion of texture was introduced by Halliday and Hasan to express the property of being a text. A text has texture and this is what distinguishes it from something that is not a text. A text derives its texture from the fact that it functions as unity with respect to its environment.
Halliday and Hasan define text as 'a unit of language in use': a text is viewed not as a grammatical unit (a clause or a sentence) but as a semantic unit, so a unit of meaning, not a unit of form.
If a stretch of language including more than one sentence is perceived as a text, there will be certain linguistic features contribuiting to its total unity and giving it texture. A text is not a collection of unrelated sentences. The existence of CONNECTIONS between sentences is an essential features of discourse: connections give a text its texture and distinguish it from a random string of unconnected sentences.
To this texture to be achieved two main concepts are used: Cohesion and Coherence.
Cohesion: it refers to the connections which have their manifestation in the discourse itself
Coherence: it refers to the connections that can be made by the listener or by the reader on the basis of their knowledge outside the discourse.