Novel is a fictional prose narrative, of substantial length. There is no specific required length that sets the novel the apart from the short story, and the terms "short novel" or "long story" are sometimes applied to prose fiction that seems too long for a short story, yet too short for a novel. Because the novel  is a narrative that does not limit itself to historical facts but creates fictional personality dwelling in an imaginary world, it is related to the epic, a long narrative poem. But the epic usually includes gods and men of exceptional or even supernatural ability, whereas the novel, descended partly from biography, memoir, and history, usually presents a world close to our own.
A more direct descendant of the epic is the romance, which in the Middle Ages was a tale in lingua Romancia. Such tales, at first in verse, later in prose, described exciting adventures_usually of separated lovers_in strange lands where the marvelous abounds. The romance, with its emphasis on the unusual, is seldom interested in the observable details of ordinary life, and adventure is far more important than character.
In Italy during the later Middle Ages and the Renaissance, a prose tale was called a novella (a short new thing). During the 19th century it was common to separate the "romance" from the "novel" on the basis of the probability of the setting or background. 
The novel may be tragic, comic, satiric, etc., though if it is satiric and the emphasis is not on story and character, it may be better to classify it simply as a satire. Gulliver's Travels, for example, is a long prose narrative, yet it is not a novel. A fundamentally different sort of travel story is the picaresque novel, presenting the exploits of a rogue (Spanish picaro).
The "picaresque novel" is usually a detailed satiric picture of middle-class life, telling of the shrewd shifts of a man who triumphs over the less bright members of the bourgeoisie whom he encounters. Because the form originated in 16th century Spain as a kind of burlesque of tales of chivalric adventures, the picaro wins in one situation after another, and the novel has an episodic structure.
While almost all novels have a fairly concrete setting, if the setting includes historical persons (Napoleon) or if the setting (French Revolution) is drawn in such detail that the reader feels that the period as well as the characters are the novelist's subject, then the novel may be termed an "historical novel". Dickens' A Tale of Two Cities, wherein no historical figure appears, can be called an historical novel by virtue of its emphasis on the setting (revolutionary France).
The Bildungsroman, or Erziehungsroman (German for "novel of development"), deals with maturation, wherein the hero becomes "civilized", becomes aware of himself as he relates to the objective world outside of his subjective consciousness. Notable example is Thomas Mann's The Magic Mountain. When the Bildungsroman is concerned specifically with the development of the artist, as are Samuel Butler's The Way of All Flesh and James Joyce's A Portrait of the Artist as a Young Man, it is sometimes termed a Kunstlerroman (German for "novel of the artist").
A novel that pays great attention to the complicated mental states of its characters is a "psychological novel". Though psychological fiction is at least a century old, in the 20th century there has been an increased exploration of the levels of mental activity. A notable kind of psychological novel is the stream of consciousness novel by William James, which records mental activity ranging from complete consciousness to unconsciousness. Its most prominent technique is the interior monologue, which reveals the minds of characters and presents not overt actions and speech or even thoughts in logical and grammatical order; rather, it attempts to present what has been called the mind's "pre-speech levels of consciousness" in such a manner as to suggest the fluid and unending activity of the mind, with all its apparent irrelevancies. Joyce's Ulysses is a stream of consciousness novel; its last forty-six pages, an uninterrupted flow of Molly Bloom's thoughts, are an interior monologue. But words printed one after the other on a page cannot, of course, precisely duplicate the welter of thoughts which-without even being verbalized-pass through the mind. The interior monologue, then, is quite as conventional as, say, the soliloquy.   
When concerning the facts of the author's life, the novel is said to be "autobiographical". The novelist speaks about himself and about the family relations. Sometimes he goes back to his early childhood or speaks about a certain age in his life. D.H. Lawrence novel "Sons & Lovers" is a great example of the autobiographical novel. It is largely autobiographical in its portrayal of spiritual and psychological development of Paul Morel; but it also deals with life in an English Midland mining village at about 1900, and it portrays the intellectual climate of the time.