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

Topic Sentence

Beginning a paragraph with a topic sentence is one of the best ways to achieve clarity and unity in one’s 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 then 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 most important characteristic of a good paragraph. Unity in a paragraph 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. When the writer changes to a new idea – one which is not consistent with the topic sentence of the paragraph – the writer should begin a new paragraph. This sometimes does not happen and hence it affects the unity of a paragraph.

Unity is important 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, this signals that the writer is moving on to a new topic.


Coherence refers to the extent to which the flow of ideas in a paragraph is easily understood by the reader. For this reason, coherence is closely related to unity. But, maintaining coherence in a paragraph is different from maintaining unity in it. 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 either on a chronological basis or in the order of importance. Conciseness lies in giving the information required clearly and in a few words.

When a writer changes main ideas or topics within a paragraph, confusion often results. To achieve coherence, then, a writer should show how all of the ideas contained 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 properly expanded 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 is underdeveloped. A good rule of thumb to follow is to make sure 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 main idea of the paragraph. 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 idea that is generated in the paragraph is not taken to its logical conclusion. Therefore, the arrangement of supporting ideas or arguments must be logical. 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 need to keep in mind the significance of unity, coherence, expansion and emphasis while we venture to construct an effective paragraph.

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