Epithets are essentially used like adjectives. Placed before a noun, they bring life to the noun they are in front of by providing a descriptor. An epithet can be more than one word, if a phrase is needed instead, then that can also be an epithet. An epithet can also be used to describe a person and can come before a person's name in poetry.
Epithets are used in poetry as a creative device. The words paint a picture in the reader's mind more effectively when epithets are used to describe a person, place or object. Epithets allow a poet to create a more melodious poem, especially when meter is used and more words are needed to create a steady meter for the poem.
Epithet poetry dates back to Greek times. Homer, the poet who wrote the works "The Iliad" and "The Odyssey" made the epithet famous by using it as his personal favorite writing device. His epithets stood out because he often used the same ones over and over, making his poems easy to remember and read by using the same descriptors for certain characters in the poems.
Any noun that has an adjective word or phrase placed in front of it can be seen as an epithet. An example of a classic epithet is "America the Beautiful," but other epithets that are used in Homer's poetry include the phrases "wine-dark sea" and "gray-eyed Athena." An epithet poem would be comprised of many epithets over and over to add color to the poem, the way Homer did with his poetry.