Length: Short stories typically range from 1,600 to 20,000 words.

Although authors and critics have debated the length of the short story throughout literary history, most agree on a minimum of 1,600 and a maximum of 20,000 words. In his own contribution to the debate, Edgar Allen Poe suggested that a short story should take 30 minutes to two hours to read.

Subject: Short stories usually focus on a single subject or theme.

Subjects or themes may range from something as mundane as a daily errand or as thrilling as a ghost tale. A single, easily contained plot is one of the hallmarks of the short story and helps shape its other characteristics.

'In medias res': Short stories usually take place in a single setting and begin 'in medias res', which means 'into the middle of things' in Latin.

In general, short stories tend to begin and end abruptly, with little to no prior information and no major lapses in time. As they involve just one plotline and are limited in word length, there is little room or need for the extended developments we frequently find in novels.

A limited number of characters: Due to the limitations of the genre, short stories typically focus on just one or a couple of characters.

As short stories usually cover such brief periods of time, even a single character may never be fully developed. 
However, historical examples, like some of Geoffrey Chaucer's 'Canterbury Tales,' may find interesting ways of involving many different people.