Paradise Lost is an epic poem—or a long narrative poem relating a hero, or heroes', journey—in the tradition of Homer's Odyssey and Iliad. Both the Odyssey and the Iliad concern sweeping narratives of war and the arc of history, unfolding over many days or even years. Paradise Lost is similarly concerned with an epic subject: the fall of man and the beginning of human history. However, the bulk of its action is less grandiose than Homer's epic poems. Rather than depicting prolonged battles, and the rise and fall of cities and civilizations—as the Odyssey and the Iliad do—Milton treats the events leading up to Eve’s seduction and decision to sin, covering just over a month of action. Milton also focuses on only a handful of characters (Satan, Adam and Eve, and God), whereas Homer's epic poems teem with both mortals and gods.
That said, Paradise Lost does feature militaristic violence—by flashing back to Satan's rebellion against God, for example—and places an emphasis on divinity and otherworldly power, just like the Odyssey and the Iliad (in which the Pagan gods reign supreme). But the reader will find elements of other genres, too, including romantic addresses (from love sonnets), unhappy twists of fate (from dramatic tragedy) and lush descriptions of nature (from pastoral). The result is a wholly unique and complex work of poetry that mirrors the complex subjects at hand: the origins of humanity and worldly evil.