Novel
A novel is a work of prose fiction of extended length. Novels tell complex stories and generally feature many characters. While a comparatively recent development, the modern novel has become the dominant literary form in western culture . In general, the novel can be distinguished from other forms in its length, complexity and the fact that, unlike the epic poem for example, it is in prose.
All of these limits have been challenged in one way or another. A short novel or novella may be considered by some to be a novel. While generally in prose, there are verse novels, Out of the Dust by Karen Hesse or Alexander Pushkin's Eugene Onegin as examples.
Antecedents
The epic poetry of the ancient world, such as the works of Homer, Virgil or the anonymous authors of even earlier epics can be considered forerunners of the novel. These, though, are in verse and are generally set in a heroic age far removed from everyday life. The medieval romance is another early form of extended narrative.
The first novels
One of the first true novels was Miguel de Cervante's Don Quixote, a story deflating the conventions of the earlier romance.