Just as a bridge over a river needs girders, columns and sound footing for maximum support of the bridge deck, an essay needs solid structure in order to efficiently support the message intended in the writing. Whether the essay consists of four, five or more paragraphs, every essay requires several essential components -- the introduction, the body and the conclusion -- in order to be considered structurally sound and for which an analysis must account.
In "Poetics," the Greek philosopher Aristotle remarked that in writing "a whole is that which has a beginning, a middle, and an end." This rather simplistic view of structure in essence provides a basis for all written communication. In the case of the essay, the beginning, middle and end become the introduction, the body and the conclusion. The three components must be composed correctly and integrate properly for the essay to achieve structural integrity.
The beginning, as the footing of the essay, rests with the introduction. While presenting the overall topic of the essay, the introduction must also indicate the parameters, or the commentary ideas, to which the writer will adhere when discussing the topic. In many cases, the writer will propose a position and will argue a defense of that position. If the reader has any doubt about the thrust of the essay after finishing the introduction, then the introduction has not served its purpose.
The body of an essay contains the critical evidence, or the columns, that defend the position the writer has taken in the introduction. Sometimes referred to as "concrete details," the evidence can consist of specific facts, examples, quotations, paraphrasing of materials, plot references or descriptions and must relate directly to one of the commentary ideas proposed by the writer. The body may consist of as many paragraphs as necessary to completely elucidate the overall subject of the essay.
Rather than merely restate the essay subject or summarize the information presented in the body, the conclusion acts as the girders that give final support to the essay topic, asserting the significance of the writer's position. The finale of the essay must convince the reader that the essay contains merit and establishes a well-constructed argument. A broad, philosophical reflection on the topic aligned with a statement enticing further exploration of the subject ensures that the reader will continue to ponder the essay topic, proof that the essay has accomplished its goal through structural integrity.