Paragraphs are an important unit in an essay. Think of them as building blocks for the architectural structure that is your essay. Each paragraph should develop a new assertion, not merely repeat that assertion in different words. When you revise a draft, read your paragraphs to make sure they are coherent: that is, that they contain only ideas and evidence relating to the topic sentence. In some essays, you may need more than one paragraph to develop an assertion fully. This group of related paragraphs is called a paragraph cluster.