A novel is a fictional piece of prose that is typically written in a narrative style and presented as a bound book. Novels tell stories, which are usually defined as a series of events described in a sequence. A novel is written down and is entirely a work of the author or authors’ imagination. There is no universally established guideline for a novel's length, point-of-view, or even establishment of a moral or philosophical point. Most of the time, though, the storyline must be somewhat complex, and there must be several angles to the narrative. The main differences between a short story and a novel are length and plot development. As a general rule, works up to 100 pages are short stories; longer works cross the line into novel territory. The only exception to this rule is the novella, which is usually held to be a work of fiction that falls somewhere between a short story and a novel.