Coherence is the logical connections that readers or listeners perceive in a written or oral text. Coherence accounts for the fact that we do not communicate by verbal means only. The traditional concept of coherence, which is solely based on relationships between verbal textual elements, is too narrow to account for coherence in interaction. Ultimately, coherence in interaction is not established in the text but created in the minds of the interlocutors in their attempt to make sense of the different verbal, perceptual, and cognitive means at their disposal “(Edda Weigand, Language as Dialogue: From Rules to Principles. John Benjamins, 2009). "Coherence is fundamentally not an objective property of the produced text. Rather, that text is a by-product of the mental processes of discourse production and discourse comprehension, which are the real loci of coherence." (T. Givón, English Grammar: A Function-Based Introduction, Vol. 2. John Benjamins, 1993).
Coherence is elusive but it has a lot to do with the way that the propositional content of texts is organised. If the content of a (written) text is organised in such a way that it fulfils the reader's expectations, it is more likely to achieve its communicative effect. This means that learners can be helped to write coherent texts through the analysis of the generic features of particular text types. This has long been the approach to teaching business, technical, and academic writing. More important still, is second-guessing the intended reader's questions, and then answering them. This means that it is important that, when doing writing tasks, students have a clear idea both of the purpose of the text, and of the intended readership. Good writers are able to "keep their reader in mind". Keeping your reader in mind does not guarantee coherence, but it would seem to be a