Expository essays explain the significance, importance, relevance, or value of some topic. An illustration or example essay does this by providing examples in support of a thesis. The thesis provides the reason for discussing the subject, its significance, importance, relevance, or value. The examples illustrate that significance, importance, relevance, or value. Examples, therefore, provide the evidence that "proves" the thesis.

In order for examples to be effective in an ilustration or example essay, the examples chosen must be representative and accurate; that is, they must illustrate what is generally true and not what may be true in a particular situation. For instance, Josh and Trevor both normally wear caps to class. If at the end of the semester, they were the only two students to receive A's, that would not be convincing examples to prove that all students who wear caps make A's. Most people would presume that wearing caps was merely coincidental to making A's. Examples are most effective when they represent the experiences of readers.

Secondly, illustration/example essays are convincing when the examples given provide both breadth and depth. A person who only has depth of understanding but who fails to see the broader implications is a narrow-minded thinker. A person who only sees the broad perspective but who lacks a deeper understanding is a shallow or superficial thinker. In the same way, an essay which does not include two or three examples discussed in depth seems shallow, but an essay which doesn't also offer a variety of examples may fail to convince the reader that the detailed examples are representative and not just special cases. Qualitative examples provide depth, and quantative examples provide breadth.

Qualitative Examples

Extended examples/anecdotes: An anecdote is a brief entertaining narrative or a tightly written, concise account of a personal experience unconnected to any larger narrative (a short, separate personal narrative). Often essays use long examples to provide depth to an essay and to make clear to the reader what is being explained. Extended examples are usually developed in one or more paragraphs. Sometimes an entire essay can center around a single anecdotal example.

Analogies: An analogy is an extended comparison, usually between two things which are very different but share a common quality. The analogy uses this common characteristic which can easily be seen in the first item of the comparison to explain and illustrate the same characteristic or quality in the second item. For instance, in an essay titled "Clipper Ship Mom," the ability of a clipper ship to weather difficult storms is uses as an analogy for the way in which the mother (who is the focus of the essay) is able to "weather the storms of her life." This particular analogy serves, then, as an extended metaphor.

Allusions: Allusions are references to things outside of the essay. Allusions can be references to historical events or people, literary works or characters, Biblical stories or characters, or cultural situations or features. Like analogies, these are used to illustrate some characteristic or quality or to expand the context of some discussion by showing its similarities with the allusion.

Hypothetical Examples: Sometimes an actual example may not be readily available to illustrate a point. In that case, writers may invent hypothetical examples as illustration. In other words, hypothetical examples are examples constructed to illustrate a point. They are convincing and effective if and when they appear reasonable. Oftentimes hypothetical examples are used in scientific writing as a way of generalizing the qualities of a variety of specific cases.

When using qualitative examples, only include those details in the story which are relevant to the thesis. However, do not skew the example to fit the thesis. Maintain intellectual integrity by only using examples which are relevant to the thesis. Don't twist an example to "make it fit" the thesis.

Quantitative Examples

Descriptive examples: These examples usually begin with a brief statement of explanation followed by a few lines of description. Descriptive examples are usually developed in several sentences or in a brief paragraph.

Lists: Oftentimes example essays include short lists of examples. These lists are most effective when they contain items which, although briefly mentioned, contain vivid details. Lists give an essay breadth by citing large numbers of relevant examples.

Confusion with other modes

Just because an essay uses examples, that does not make it an illustration/example essay. To be an illustration/example essay, the essay must develop a topic which is illuminated or illustrated by examples, that is, the examples reveal the significance, importance, relevance, or value of the topic. Narrative, descriptive, classification/division, cause/effect, definition, and argument essays all routinely use examples to achieve their purposes. But in those cases, the examples are used as strategies within the essay rather than as the principle organizaing pattern of the essay.