A competing strategy for a writer is to first spend some time characterizing the protagonist(s), the principal problem(s) he faces, and the obstacles or opponents he must overcome. In this strategy, a tendency exists for the writer to load the development of a story with too much detail, before a reader might even have had a chance to become invested in the characters or the problem of the story.
Depending on our chosen writing strategy, if we need to reveal some important facet of the character's life, or the development of the problem, before the time of the narrative, i.e., a backstory, the writer will often resort to a 'flashback.' The flashback can be as short as a few sentences, or it might encompass an entire chapter embedded within the narrative of the current story. Regardless, an effective flashback can be difficult to use without disturbing the 'fictional dream' (John Gardner, The Art of Fiction) for the reader, and possibly losing our reader.
It was interesting to note how how author Marilynne Robinson addressed the absence of any backstory for an otherwise quite interesting character, Lila, who appeared in Gilead, her 2005 Pulitzer Prize winning novel. Lila was an intriguing young woman who appeared out of nowhere to marry a much older preacher in this spare, beautifully written story set in the mid-ninteenth century Iowa plains.
Robinson devoted a subsequent novel, Lila, to explain this unique woman. I'm in the middle of reading it, and a confluence of yesterdays's life drawing session, see my watercolor sketch above, and this week's evening readings of Lila, gave rise to the musings about a use of backstory in fiction. I hope it's been interesting.