Allegory is a figurative mode of representation conveying meaning other than the verbal. Allegory communicates its message by means of symbolic figures, actions or symbolic representation. Allegory is generally treated as a figure of rhetoric, but an allegory does not have to be expressed in language: briefly, an allegory is a device used to present an idea, principle or meaning, which can be presented in literary form, such as a poem or novel, or in visual form, such as in painting or drawing.
As a literary device, an allegory in its most general sense is an extended metaphor. As an artistic device, an allegory is a visual symbolic representation. An example of a simple visual allegory is the image of the grim reaper. Viewers understand that the image of the grim reaper is a symbolic representation of death. Another example is the female allegory of justice. Such visual representations have raised the question why so many allegories in the history of art, representing male gendered realities, are of female sex.
Not every fiction with general application is an allegory.