In his mock-epic Don Juan, Lord Byron provides a list of epic conventions even as he parodies them:

My poem 's epic, and is meant to be

Divided in twelve books; each book containing,

With love, and war, a heavy gale at sea,

A list of ships, and captains, and kings reigning,

New characters; the episodes are three:

A panoramic view of hell 's in training,

After the style of Virgil and of Homer,

So that my name of Epic 's no misnomer.

Some of these items are clearly not a necessary part of the definition of heroic epic. The catalogue of ships, for instance, is a specific reference to the Iliad, rather than a feature of all epics, while the descent into the Underworld, an important part of several epics, is still not common to all. However, it is possible to give a few general features which define the epic genre. An epic poem is long and is generally divided into books, traditionally twenty-four or twelve. It tells the story of a hero, a man of noble birth and great physical courage, who performs extraordinary feats. It is composed in the archolect, a high style, which emphasizes the nobility of the subject.

The story told in heroic epic should combine human drama with cosmic significance. The gods are often involved in the outcome, and the hero may, like Achilles and Aeneas, be of semi-divine birth or may, like Odysseus, be under the patronage of one particular god or goddess. More recent epics present additional complications. For instance, Paradise Lost is clearly an epic, but who is the hero? Adam, the Son, and Satan have all been suggested as candidates, whereas there is clearly no such controversy in the case of the Odyssey.