Purpose: A narrative essay tells a story, often from the perspective of the writer.
Introduction: Sets the scene for the story and introduces the plot.
Body: The body covers the plot, telling the story up to its climax.
Conclusion: Reflects upon the climax to the story, refers to the main reason for the story and discusses the point which the story makes.
Language: Often uses the first person.
Other considerations: Descriptive or emotive language may be necessary to help the reader to empathize, so word choice is important.