Epic poems begin with the narrator's statement of the poem's subject and his invocation to, or calling upon, a muse or other divine entity to assist him in taking on the task of telling his story. All epic poems have an "in medias res," meaning "in the midst of things," opening. That is, the poem opens in the middle of the story's action, not the beginning.
Epic poems are usually set in the entire known world of a particular culture or the entire universe, including the heavens and the underworld. Actions, events and journeys that should take years often take place in just days or as little as hours.
An epic poem's main character is a heroic figure who represents a particular culture's idea of what strengths and virtues make someone a hero. However, the epic hero's weaknesses and failings are as evident as his strengths and virtues. The epic hero is often a warrior, leader, part human and part god, and his actions can occur while on a journey or while pursuing a conquest. Whether an epic poem is structured around a journey or war, the hero's quest includes dangerous obstacles that test his strength, endurance, courage and craftiness. However, the hero does not confront and battle his primary opponent until the climax of the story.
Gods and other deities often play a role in the outcome of events, whether for good or evil, as they assist the hero or become an obstacle in his quest. Whether an epic poem is structured around a journey or a war, the hero also often descends into the underworld, where his strengths and other abilities are tested.
Epic poems often contain epic similes, which are long, highly descriptive similes that clarify the subject. Like a regular simile, the epic simile makes a comparison starting with "like" or "as." However, the epic simile is a style device used in epic poetry to prolong action at a critical point for suspense.
Epithets, characterizing words or phrases applied to a person or thing and sometimes used in place of their actual name or title, are common in epic poetry. Patronymics, calling a son by his father's name, are also used frequently as a form of address between characters. For example, Achilles in "The Iliad" is often addressed as "Son of Peleus."
The hero and other important characters often make long, formal speeches, such as challenges or points of debate, in the middle of action. These speeches end with "thus he spoke" or similar phrases to clarify that the character was speaking, not the narrator. Epic poems also contain lengthy histories and descriptions of important items, such as a sword, used by the hero or other important characters.