What is the controlling idea of a paragraph?

The controlling idea of a paragraph is the main point or central focus of the paragraph. It is usually expressed in a single sentence, known as the topic sentence, which is typically located at the beginning of the paragraph. The controlling idea provides a framework for the paragraph and guides the development and organization of the supporting details, examples, and explanations that follow. The supporting sentences in the paragraph should work together to support, develop, and elaborate on the controlling idea.