A novella is a work of narrative fiction that is shorter than a novel but longer than a short story. The length of a novella varies, but it is generally recognized as a work of prose fiction with a word count between 17,500 and 40,000 words. Novellas may be intended to be read at a single sitting, like short stories, and thus produce a unitary effect on the reader. They tend to contain a concrete symbol, which is the narratives focal point. Novellas may be written in a variety of styles, on a range of subject matter or themes. Some examples of novellas include "The Strange Case of Dr. Jekyll and Mr. Hyde" by Robert Louis Stevenson, "The Time Machine" by H.G. Wells, "Animal Farm" by George Orwell, and "We Have Always Lived in the Castle" by Shirley Jackson. Writing a novella has its advantages, as it presents an excellent opportunity to experiment with form and style.