A topic sentence opens a paragraph and states or suggests what the body of the paragraph will discuss. To maintain clarity, topic sentences must be specific and focused, giving a clear introduction to the analysis or description that follows. Topic sentences can also be used as transitional devices, helping the author move from the information in prior paragraphs to a new or extended point. Though topic sentences are not always required, they are frequently used in analytical and creative writing.
The topic sentence serves as the opening statement of a paragraph. Placing the main point in the first sentence allows the reader to quickly comprehend what the body will cover in detail. Using the topic sentence as a succinct statement of the body of the paragraph can also benefit the writer: In timed essay writing, one strategy is to sketch out the topic sentence of each paragraph before beginning the essay, as this allows the writer start writing with an existing plan for the order and flow of ideas he or she will present.
Specificity is important to the crafting of a good topic sentence. An opening line that is too broad may leave the reader confused as to which specific points are being discussed. For example, the sentence “Unwanted pets may end up at the shelter for many reasons, but there are few good solutions for them,” might be considered too broad, since it is unclear whether the paragraph will discuss the many reasons pets are at shelters, or the paucity of solutions to the problem. A more specific topic sentence, such as “Unwanted pets end up at shelters for many reasons, including illness, loss of family income, and neglect,” helps set up the body of the paragraph by briefly explaining what will be discussed.
In addition to providing specificity, topic sentences can also serve as a means of transition to a new statement. If a writer wishes to use the information from the previous paragraph to further a point, he or she might include an opening clause that references the relevant material. For instance, using the last example, the next paragraph about pets in shelters might begin, “With so many reasons why pets end up in the pound, it is easy to see why overcrowding at local shelters is a problem.” By referencing the last paragraph, the writer can then build on the knowledge already gained to lay out a new point or extend an existing argument.
Not all paragraphs use or require topic sentences. Paragraph that list steps or actions, such as in cooking recipes, often do not need a topic sentence for clarity. In creative writing, many professionals eschew this form of writing altogether, considering it too formal and restrictive for a natural flow of ideas. Nevertheless, they are often required in essays, term papers, and other forms of required writing exercises. In general, however, a topic sentence is best used when it helps clarify ideas or arguments for either the writer or the intended audience.