Short answers, pulled from the story.
Fiction is any creative work, chiefly any narrative work, that portrays individuals, events, or places that are imaginary or imagined in ways that depart from reality. Its portrayals are inconsistent with fact, history, or plausibility. In the narrow traditional sense it refers to written prose such as novels, novellas, and short stories.
Beyond written prose, fiction encompasses imaginary narratives in any medium. These include live theatrical performances, films, television programs, radio dramas, comics, role-playing games, and video games, along with fables, legends, myths, fairy tales, narrative poetry, plays, animated cartoons, anime, and manga.
Speculative fiction adheres less to realistic or plausible individuals, events, or places, and includes fantasy, alternative history, and science fiction. Realistic fiction adheres more closely, using a basic setting of time and location that is real and events that could believably happen, and includes historical fiction.
Literary fiction is often character-driven, examines the human condition, uses language in an experimental or poetic fashion, and is considered serious as art, while genre fiction makes plot the central concern. The two are not mutually exclusive, and major literary figures have used science fiction, crime fiction, and romance to create works of literature.
The structure of the modern novel was developed by Miguel de Cervantes with Don Quixote in the early-17th century. The novel then became a primary medium of fiction in the 18th and 19th centuries, often tied to Enlightenment ideas such as empiricism and agnosticism.
Fictionalization is the use of real events or real individuals as direct inspiration for imaginary events or individuals, narrowed to dramatization for visual works in theatre and film. The opposite circumstance, where the physical world seems influenced by past fiction, is described as life imitating art, a phrase popularly associated with Oscar Wilde.
Written fiction in prose is distinguished by length, with a short story commonly comprising fewer than 7,500 words, a novella typically running 17,500 to 40,000 words, and a novel 40,000 words or more. Examples of novellas include Strange Case of Dr Jekyll and Mr Hyde from 1886 and Heart of Darkness from 1899.