An epic is normally defined as a long narrative poem about the exploits of a national hero. Epics carry a culture's history, values, myths, legends, and traditions from one generation to the next. There are certainly many works of literature that are considered epics, such as Gilgamesh, Beowulf, The Illiad, The Odyssey and Sundiata. They all share the following characteristics:
1) They take the form of a long narrative poem about a quest, told in formal, elevated language.
2) They narrate the exploits of a larger-than-life hero who embodies the values of a particular culture
3) They begin with a statement of subject and theme, and, sometimes, a prayer to a deity
4) They deal with events on a large or "epic" scale
5) They use many of the conventions or oral storytelling, such as repetition, sound effects, figures of speech, and stock epithets
6) They often include gods and goddesses as characters
7) They mix myth, legend and history
Epics are well worth reading as they contain excellent adventures but also are valuable cultural gems that act as great teachers of a given society's values and core beliefs.