What is an exposition?

The word exposition partly comes from the root, expose. Hence, the function of an exposition is to expose the issue which it targets, and show more about the topic. An exposition is a form of writing where information that is difficult to understand is conveyed. Such a piece of writing cannot be one-sided, and has to consider all the possible perspectives whic exist in an issue, as an exposition is supposed to expose more about the issue.
Of course, an exposition can also mean a public exhibition if taken literally. In a way, expository writing does share some similarities with an exibition, mainly that it has to at least increase the knowledge or perception of the audience which reads it of the issue at hand.