How were short stories, novellas, and novels defined?

Short stories, novellas, and novels could usually be distinguished by the number of words, plot, characters, and so on. 1. Number of words: Short stories usually have fewer words, usually less than 2000 words. The plot and characters are relatively simple, and the theme is often more singular. Medium-length novels usually have between 3000 to 8000 words. The plot and characters are more complicated and the theme is more diverse. Long novels usually have more than 8000 words or even more than 1 million words. The plot and characters are more complicated and the theme is more profound. 2. Plot: Short stories usually win with the plot, focusing on the compact and rhythm of the story, the relationship between the characters and the characters is relatively simple; medium-length novels pay more attention to the development and complexity of the plot, and the relationship between the characters and the characters is more complicated, which may involve a deeper theme. 3. Character: Short stories usually focus on shaping the image and character of the characters. The number of characters is small; novellas focus more on the number and depth of characters. They may shape the image of multiple complex characters and explore their inner worlds and relationships in depth. The definition of short stories, novellas, and novels depended on the reader's expectations and reading needs. Different readers might have different preferences and evaluations for different types of novels.