In the fiction world we are given a fairly standard set of guidelines for exactly what constitutes a novel versus a novella, or a novelette versus a short story.
Beyond that, however, the rules grow murky.
What, exactly, is flash fiction?
That depends on who you ask.
In very general terms we can define flash fiction as any story shorter than acceptable short story length (usually 2000 words minimum). But anyone publishing flash fiction can arbitrarily pick and choose word count limits and still call it flash fiction, AND can choose their own name for it: short-short, sudden, postcard, minute,
smokelong, fast, furious, skinny, and micro as just a few examples.
Historically, flash fiction has been around for thousands of years--think Aesop--but has only been known under the flash moniker since 1992 when Editor James Thomas used the term to title his short story anthology, Flash Fiction: Seventy-Two Very Short Stories. Before 1992, before flash was recognized as a separate form, greats like Chekov, O. Henry, Kafka, Ray Bradbury, H.P. Lovecraft, Mark Twain, and Kurt Vonnegut wrote flash-length stories.
For the 21st Century writer, the form is wide open, with markets everywhere now accepting very short stories and readers everywhere gobbling up a form that seems made for the frantic lifestyle we've come to lead. Stories that can be written, edited, and submitted in a matter of hours. Stories that can be read in the length of time it takes to smoke a cigarette, or drink a cup of coffee, or wait for a train. Stories short enough to be enjoyed between classes, or while waiting at the doctor's office, or in the supermarket checkout line.
But there is more to flash fiction than merely length.
For writers, the form presents a new challenge. How do I tell a complete story in so few words?
Granted, many writers use the form in writing and publishing vignette (also known as stream of consciousness or slice of life). And it lends itself beautifully to that. Those types of stories rarely work well at longer lengths anyway, and the shorter form is a wonderful way for the writer to explore the beauty of language and emotion without exhausting their appeal to an audience that might not otherwise read a high literary style. Other types of flash include Nonfiction Narratives, which, based on length, are dumped into the flash 'fiction' category despite not actually being fiction; and Prose Poetry, which tends to be a VERY literary styles in which language trumps all else.
In my opinion it's relatively easy to present a vignette in 500 or 700 words. One of the true challenges in writing flash fiction is in the careful crafting of a complete story--characters, setting, plot development, resolution and all. A writer who chooses to study the form and accept this challenge will, invariably, come out the other end of it a better writer.
It is tempting to use the idea of flash fiction and apply it to something more akin to a story synopsis. This is not flash fiction. How do you tell? If dialogue is sacrificed for explanatory narrative, if your paragraphs are long and blocky, if you find yourself 'telling' too much and 'showing' very little, if more than 10 to 20% of the story is taken up with description rather than action, if what you're presenting seems like part of a larger story, is a scene from a novel, or an episode in a serialized story.
Learning the art of complete-story flash fiction forces a writer to examine every word choice, every character description, every plot point with precision and economy. Some flash writers quip that if Robert Jordan had studied flash fiction first his Wheel of Time series might have been a few hundred pages instead of 15 doorstop-sized volumes that he never actually lived to complete. I'm sure Robert Jordan fans would argue that fifteen volumes wasn't enough. Having never read Jordan's series, I suspect the truth is somewhere in between.
In the end, writers should understand that what constitutes flash fiction is at the discretion of the publisher, and to become a successful author in the form requires two things: First, that you be familiar with the markets to which you intend to submit; Second, that you ALWAYS study submission guidelines before submitting.
For more on writing flash fiction, visit Managing Story Length and Thirteen Tips for Writing Flash Fiction.