Cohesion, or coherence, is the intangible glue that holds paragraphs together. Having good coherence in a writing project means that your ideas stick together and flow smoothly from one sentence to the next, so that readers of your work can easily understand where you are taking them. Without cohesion, a written work can seem choppy and may not flow well; a lack of coherence challenges the reader and can hurt comprehension, thus rendering your attempt at communication ineffective at best.