Genre is any style or form of communication in any mode with socially agreed-upon conventions developed over time. In popular usage, it normally describes a category of literature, music, or other forms of art or entertainment, based on some set of stylistic criteria. Often, works fit into multiple genres by way of borrowing and recombining these conventions. Stand-alone texts, works, or pieces of communication may have individual styles, but genres are amalgams of these texts based on agreed-upon or socially inferred conventions. Some genres may have rigid, strictly adhered-to guidelines, while others may show great flexibility.

Aristotle's Poetics is the earliest surviving work of Greek dramatic theory and the first extant philosophical treatise to focus on literary theory. In this text Aristotle offers an account of ποιητική, which refers to poetry and more literally "the poetic art," deriving from the term for "poet; author; maker," ποιητής. Aristotle divides the art of poetry into verse drama, lyric poetry, and epic. The genres all share the function of mimesis, or imitation of life, but differ in three ways that Aristotle describes:Differences in music rhythm, harmony, meter, and melody. Difference of goodness in the characters. Difference in how the narrative is presented: telling a story or acting it out.