Flash fiction is a style of fictional literature or fiction of extreme brevity. There is no widely accepted definition of the length of the category. Some self-described markets for flash fiction impose caps as low as three hundred words, while others consider stories as long as a thousand words to be flash fiction.
There are lots of sites covering this sub-section of creative writing. The fact I had never heard the phrase before just goes to show how inexperienced I am as a fiction writer.
There are competition for writers of flash fiction and details can be found at http://www.jbwb.co.uk/writingcomps.htm
I am going to encourage Eve and Ella to submit an entry. I might even have a go myself.