In literature, an allegory is a rhetorical device that is most easily understood as an extended metaphor, or a story whose characters and plot have symbolic significance outside of the text.
This allegorical meaning is often social, religious or political in nature.
If a work of literature is said to be allegorical, this means that the story can also be interpreted as 'meaning' or representing something else.
The following works of fiction are widely considered to be allegories:
The Chronicles of Narnia: This series of books by C. S. Lewis is often interpreted as an allegory for Christianity. Aslan, the self-sacrificing lion, can be seen to represent Jesus, the evil White Witch as Satan tempting Edmund, and Edmund himself as Judas.
Animal Farm: This novella by George Orwell is intended as an allegorical critique of the Russian Revolution and dictator Stalin's rise to power. It uses the farmyard setting and characters to retell the story of the emergence of Soviet communism.
The Wonderful Wizard of Oz: Both the novel by L. Frank Baum and the film adaptation can be interpreted as an allegory for the economic depression of late 19th century America, with the Emerald City implying fraud (the colour green is associated with money, and the discovery that the city is not green at all suggests deceit).