What does a "topic sentence" do?

A topic sentence serves as a crucial element in writing, as it summarizes the main idea of a paragraph. It typically appears at the beginning of a paragraph and encapsulates the essence of what the paragraph will discuss. This allows readers to grasp the central theme quickly, guiding their understanding of the content that follows. By focusing on the primary argument or point, the topic sentence sets the direction for the details, examples, and explanations provided in the rest of the paragraph. Therefore, it lays the groundwork for coherent and structured writing, enabling the reader to follow the author’s line of thought effectively.