An essay is a piece of writing that discusses an issue or problem. It includes an introduction with a thesis statement, body paragraphs with arguments and evidence, and a conclusion. Essays are structured with an introductory paragraph, 3 body paragraphs, and a concluding paragraph. To write an essay, a writer should brainstorm ideas, research the topic, develop paragraphs with a topic sentence and supporting details, and use linking words to connect ideas. The introduction should present the topic and thesis statement, while the conclusion should summarize the main points and end with a statement of the writer's opinion.