LONG -- The shortest epics generally exceed 1,000 lines; shorter heroic works are sometimes called "heroic poetry," although length is rarely the only distinguishing factor. The longest epics run to hundreds of thousands of lines -- many times the length of the Iliad.

NARRATIVE -- The subject matter of epic traditionally is divided into four groups: shamanistic (the Kalevala), heroic, (the Iliad), historical (the Prince of Orange cycle), and romantic (the Book of Dede Korkut).

POEM -- A few cultures (among them Hebraic, Icelandic, and Celtic) developed a prose tradition instead of a poetic one. Epic-like prose narratives are sometimes called sagas (after their name in Icelandic).

ORAL IN STYLE -- As a genre, epic developed in oral tradition. An old classification system distinguished:

primary epics -- those in oral tradition (the Serbo-Croatian epics of Crown Prince Marko)

secondary epics -- written texts derived from oral tradition (the Iliad, Beowulf)

tertiary epics -- literary imitations (Paradise Lost)

In fact, the boundaries between orality and literacy are much less distinct than these categories imply.