A literary genre is a category of literature. Genres may be determined by literary technique, tone, content, or length (especially for fiction). They generally move from more abstract, encompassing classes, which are then further sub-divided into more concrete distinctions. The distinctions between genres and categories are flexible and loosely defined, and even the rules designating genres change over time and are fairly unstable.
Genres can all be in the form of prose or poetry. Additionally, a genre such as satire, allegory or pastoral might appear in any of the above, not only as a subgenre (see below), but as a mixture of genres. Finally, they are defined by the general cultural movement of the historical period in which they were composed.
The concept of genre began in the works of Aristotle, who applied biological concepts to the classification of literary genres, or, as he called them, "species" (eidē). These classifications are mainly discussed in his treatises Rhetoric and Poetics.
Genres are categories into which kinds of literary material are organized. The genres Aristotle discusses include the epic, the tragedy, the comedy, dithyrambic poetry, and phallic songs. Genres are often divided into complex sub-categories. For example, the novel is a large genre of narrative fiction; within the category of the novel, the detective novel is a sub-genre, while the "hard-boiled" detective novel is a sub-genre of the detective novel.
In the Rhetoric, Aristotle proposed three literary genres of rhetorical oratory: deliberative, forensic, and epideictic. These are divided based on the purpose of the orator: to argue for future policy or action (deliberative), discuss past action (forensic), or offer praise or blame during a ceremony (epideictic).
In the Poetics, Aristotle similarly divided poetry into three main genres: the epic, tragedy, and comedy. In the case of poetry, these distinctions are based not on rhetorical purpose, but on a combination of structure, content and narrative form.
