What is the role of the topic sentence in a paragraph?

The topic sentence serves a crucial role in a paragraph as it succinctly summarizes the main idea or point that the writer intends to convey. It acts as a guide for the reader, outlining what the paragraph will discuss and establishing a focus for the subsequent sentences. By clearly presenting the central theme, the topic sentence helps to ensure coherence and unity within the paragraph, allowing readers to understand the connection between the details that follow and the overarching message. This structure is essential for effective writing, as it assists readers in navigating through the content and grasping the writer's intent.