An essay is a short non-fiction work about a subject that can be formal or informal in tone and style. It has an introduction that introduces the topic and thesis, body paragraphs that provide evidence and support the thesis, and a conclusion that restates the thesis without introducing new ideas. The different types of essays are descriptive, narrative, expository, and persuasive; and formal essays are more informative while informal essays are more personal. Effective essays have elements like audience, purpose, subject, point of view, theme, mood, tone, and style.