An essay is a piece of writing that has more than one or two paragraphs and is organized in a specific way. An opinion essay expresses an opinion about something. There are three important parts of a good opinion essay: Introductory Paragraph Introduces your topic. Includes a thesis statement that states the main idea of the essay (your opinion) Body at least I paragraph) Each paragraph of the body has a topic sentence and supporting details. The details can be reasons, facts, examples, and explanations. Concluding Paragraph Restates the main idea expressed in your thesis statement.