Where the term comes from
Merriam-Webster defines backstory as a story that tells what led up to the main story or plot, and dates the word's first known use to 1982. Wikipedia describes it as a set of events that establishes a character's past or precedes and leads up to the main plot, usually used to lend depth or believability to the main story.
The same entry lists the ways backstory can reach the reader: flashbacks, dialogue, direct narration, summary, recollection and exposition. It adds that backstory is usually revealed, in part or in full, as the main narrative unfolds, and that a creator may also invent a backstory that exists only for their own use. That last point matters in practice, because a writer can know a good deal about a character's past without printing any of it.
An example
Ines Calder is a ferry mechanic who flinches whenever a ratchet clicks. The backstory is that, ten years earlier, she was the engineer on a boat whose winch failed and dropped a loaded cart into the harbour. It is never narrated in chapter one. Instead the reader sees her step back from a coworker's tool bag, and then a deckhand teases her about the way she avoids the winch house. In chapter twelve her new apprentice asks why she always checks the pawl twice. Ines answers in two sentences and returns to work. The reader now understands every earlier flinch, and no scene has stopped to deliver a biography.
Common mistakes
- Opening with pages of history before the reader cares about the character.
- Including backstory that changes nothing about what the character does now.
- Explaining every habit, so the character has no mystery left.
- Contradicting the past later in the book because it was never written down.
- Holding back the one fact the reader needs to understand a major choice until after the choice is made.
How to check your manuscript
List the three past events that most shape your main character. Beside each, find the scene where it first affects a choice on the page, and the scene where the reader learns it. If the reader learns it long before it matters, or never learns it, adjust the timing. Another test is to cut a backstory passage and see whether any later scene stops making sense. For related terms, see flashback, show, don't tell and character arc.
In Musael, world and characters shows where each character is mentioned in the text, so you can see which scenes already reveal a piece of someone's past.