An effective paragraph often focuses on one main idea. A good way to achieve such paragraph unity is to state the main idea clearly in one sentence and then relate all the other sentences in the paragraph to that idea. The sentence that presents the main idea is called the topic sentence.
FOR MULTILINGUAL WRITERS
Native readers of English generally expect that paragraphs will have an explicitly stated main idea and that the connections between points in a paragraph will also be stated explicitly. Such step-by-step explicitness may strike you as unnecessary or ineffective, but it follows the traditional paragraph conventions of English.
Announcing the main idea in a topic sentence
The following paragraph opens with a clear topic sentence, and the rest of the paragraph builds on the idea stated in that sentence:
Our friendship was the source of much happiness and many memories. We grooved on every new recording from Jay-Z. We sweated together in the sweltering summer sun, trying to win the championship for our softball team. I recall the taste of pepperoni pizza as we discussed the highlights of our team’s victory. Once we even became attracted to the same person, but luckily we were able to share his friendship.
A topic sentence does not always come at the beginning of a paragraph; it may come at the end. Occasionally a paragraph’s main idea is so obvious that it need not be stated explicitly in a topic sentence.
Relating each sentence to the main idea
Whether the main idea of a paragraph is stated in a topic sentence or is implied, make sure that all other sentences in the paragraph contribute to the main idea. In the preceding example about friendship, all of the sentences clearly relate to the point that is made in the first sentence. The result is a unified paragraph.