Where the term comes from
Merriam-Webster lists several senses of exposition, including a setting forth of meaning and discourse designed to convey information or explain what is difficult to understand. It also gives the musical sense, the first part of a sonata-form movement in which the thematic material is presented. The earliest recorded use of the word dates to the 14th century.
In fiction, Wikipedia defines narrative exposition as the insertion of background information within a story, which can be about the setting, characters' backstories, prior plot events or historical context. It describes indirect exposition, or incluing, as a worldbuilding technique in which the reader is gradually given background without noticing, through dialogue, flashbacks, thoughts, background details or a narrator's account. The article credits Rudyard Kipling with an early clear use of the technique, in stories set in India for readers who did not know the country. It also warns against the "idiot lecture", in which characters tell each other things they would already know for the audience's sake.
An example
Teodor Linnet is writing a courtroom drama set in a town that banned lantern oil after a fire. He needs the reader to know the ban exists before the trial starts. His first draft has the judge read the statute aloud for two pages. In the second draft, a defence lawyer, Perrin Cass, arrives at the courthouse with a flask of oil hidden in her coat and sweats through a security check. The reader learns the rule, its penalty and Perrin's motive in three paragraphs, and no one stops to explain. The rest of the town's history comes out in witness cross-examination, one useful fact at a time.
Common mistakes
- Delivering information before the reader has any reason to want it.
- Writing "as you know" dialogue in which two characters recite facts both of them already hold.
- Treating all exposition as bad and leaving the reader unable to follow events.
- Putting it all in the opening chapter, when the reader has no investment in the world yet.
- Explaining things the reader would infer from the scene.
How to check your manuscript
Highlight every sentence that gives the reader information about the past, the setting or the rules. Beside each, note what the point-of-view character wants at that moment. If the answer is "nothing", the passage is probably standing apart from the story. Try attaching the same facts to a conflict, a mistake or a question from a character who does not know. For related terms, see worldbuilding, pacing, in medias res and show, don't tell.
In Musael, world and characters keeps your lore in entries beside the draft, so you can choose which facts a scene needs and leave the rest where it is.