A genre is a classification of works of art and performance art, whether in literature, music, visual arts, media or any of the other arts. Philosophers and critics have sought to classify art since the classical period, one of the great early examples being Aristotle's poetics.
Notions of genre are complicated by the fact that genre is assigned based on imprecisely-defined criteria, that these are linked to prevailing culture and thought, and so they change over time. New genres can emerge based on social changes. Works of art may fit easily into established genres, or may cross over into different genres, or may be difficult or impossible to classify.