A paragraph is a self-contained unit of writing that consists of a group of sentences focused on a single topic or idea. It typically begins with a topic sentence that introduces the main point of the paragraph, followed by supporting sentences that provide further explanation, evidence, or examples. A well-written paragraph is cohesive and coherent, with each sentence logically connected to the others to create a clear and organized flow of information. Paragraphs are used in writing to break up text, organize ideas, and guide the reader through the content in a structured and digestible manner.