Short stories are linked to the oral storytelling tradition, including the telling of fables and fairy tales. However, in written form, they gained popularity in print well after novels were established. It's generally believed that short stories came to be a recognized printed genre in the early 19th century. A couple of the earliest American writers to specialize in short stories were Edgar Allan Poe and Washington Irving.
A short story can range from as few as 500 to 600 words up to 5,000 or 6,000 words. If a short story is longer than about 7,000 words, it is more likely to be called a "novelette" or a "novella." Short stories under 500 words are usually called "flash fiction." Occasionally, stories of exactly 100 words are called "drabbles."
Short stories can be divided into "slice of life" and more traditional storytelling forms. A "slice of life" short story paints a picture of a moment in time in a character's life, but may not have much of a plot and little conflict. Traditional short stories have a plot, although usually a less complex one than a longer work would have. Short stories are written in every genre, ranging from pulp science fiction to romantic tales to literary fiction.
Because there is less space to tell the tale, most short stories contain spare amounts of exposition and scene-setting. Most, but not all, short stories start in the middle of the action ("in medias res"). Short stories, unless they are "slice of life," do have a central conflict and a plot, though the plot is less complex than that of a novel. Ideally, the main character changes, if only in a small way, over the course of the story.
Members of the reading public sometimes assume that it must be easier to write a short story than a novel. However, this is often untrue. Some famous novelists have been quoted as saying they find writing short stories difficult, and every time they try to write one, it turns into a longer work. Writing short stories is a challenge because most of the elements of a novel must be included in the story, but in extremely compact form. A novelist has a lot of room in which to set scenes, flesh out characters and include background exposition. A short story writer must include most of this information while also leaving room to create a conflict and develop a plot in fewer than 7,000 words.