What is an essay? Discuss its principal type.
Your basic essay is approximately 5 paragraphs unified around a central theme or idea. The most common essay types are narrative, definitive, and persuasive.
The easiest way to craft an essay is to use the "sandwich" method. You will have an introductory paragraph and a concluding paragraph which will basically state the same material at the beginning and end to frame the "meat" of the essay.
Your 2nd through 4th paragraphs are the middle portion of the sandwich and cover various aspects of your essay through the use of details and examples.
For more information see the link I have posted.