Reading Time: 3 minutes

A paragraph is a collection of sentences relating to one main idea or topic. Good writing in any form has the following characteristics, which are true of well-written paragraphs: a topic sentence, unity, coherence, expansion, and emphasis.

Topic Sentence

Beginning a paragraph with a topic sentence is one of the best ways to achieve clarity and unity in writing. The function of a topic sentence is to describe what the paragraph will be about, such that the reader has clear expectations about what will follow. An effective topic sentence typically contains only one main idea. The remainder of the paragraph develops that idea more fully, offering supporting points and examples. After reading a topic sentence, one should be able to anticipate the type of information contained in the rest of the paragraph. If the remainder of the paragraph does not fulfil the “promise” of the topic sentence, the paragraph will lack unity, coherence and adequate development.


Unity is the essential characteristic of a good paragraph. Unity in a paragraph stands for the togetherness of ideas. It refers to the extent to which all of the ideas contained within a given paragraph “hang together” in a way that is easy for the reader to understand. Ideally, a paragraph should have one central idea outlined through the topic sentence and the subordinating sentence ideas -which help the main idea to come to the fore. The writer should begin a new paragraph when the writer changes to a new idea – one inconsistent with the paragraph’s topic sentence. This sometimes does not happen, and hence, it affects the unity of a paragraph.

Unity is essential because it aids the reader in following along with the writer’s ideas. The reader can expect that a given paragraph will deal only with one main topic; when a new paragraph begins, the writer moves on to a new topic.


Coherence refers to the extent to which the reader quickly understands the flow of ideas in a paragraph. For this reason, coherence is closely related to unity. But, maintaining coherence in a paragraph differs from preserving unity. Clarity, coherence and conciseness are the three Cs essential to writing. Clarity means the main idea and the supporting points are expressed in a simple and precise manner. Coherence refers to the relationship between the ideas presented. It is a rational arrangement of ideas chronologically or in the order of importance. Conciseness lies in giving the information required clearly and in a few words.

Confusion often results when a writer changes a paragraph’s central ideas or topics. To achieve coherence, a writer should show how all of the ideas in a paragraph are relevant to the main topic.

Expansion and Emphasis

Alongside maintaining coherence and unity, it is also required that the idea that is introduced in a sentence is expanded correctly and emphasized. A paragraph is adequately developed when it describes, explains and supports the topic sentence. If the “promise” of the topic sentence is not fulfilled, or if the reader is left with questions after reading the paragraph, the paragraph has not been adequately developed. Generally speaking, a paragraph that consists of only two or three sentences needs to be developed more. A good rule of thumb is to ensure that a paragraph contains at least four sentences that explain and elaborate on the topic sentence.

Generally speaking, a paragraph should contain between three and five sentences, all of which help clarify and support the paragraph’s main idea. When a writer begins a new paragraph, it signals to the reader that the writer is changing thoughts or ideas or is moving on to discuss a different aspect of the main idea. Some paragraphs fail to click with the reader simply because the concept generated in the paragraph is not taken to its logical conclusion. Therefore, the arrangement of supporting ideas or arguments must be rational. You may use one of the following criteria while arranging the ideas. Simple to complex or vice versa, general to specific or vice versa, high to low priority ideas.

Appropriate vocabulary and grammatically correct sentences must be used. Thus, we must remember the significance of unity, coherence, expansion and emphasis while constructing an effective paragraph.