Here's why:
* Unity: Each sentence in a paragraph focuses on a single main idea or topic. They work together to develop that idea.
* Cohesion: The sentences flow smoothly from one to the next, using transitions, pronouns, and other devices to create a clear connection.
* Development: A paragraph doesn't just list facts; it expands on the main idea with examples, details, explanations, or arguments.
Think of a paragraph as a mini-essay, focusing on one aspect of a larger topic.