A narrative poem is often a long poem, sometimes even resulting in a book. Homer's "The Iliad" and "The Odyssey" are classic examples of the narrative poem in the form of a book. The story element tells the tale while the form and presence of the work is written in a poetic manner. In the case of a book, the narrative poem tells a detailed account of the character's struggles.
Any song that tells a story is a type of narrative poem. In many cases, the song versions of a narrative poem take the form of a ballad. The song is a relatively short narrative poem that tells a short story of a single event or idea. For example, it might tell of a break-up or an event that occurred in the narrator's life or in the life of the character. Many songs fall under the narrative poem category because most songs tell some portion of a story.
Lays are the type of long narrative poems which are not an epic or book in length, but take several stanzas, couplets or stophes to tell the tale. According to the website Types of Poetry, lays were common during the Middle Ages and told by minstrels or French trouveres. The poem told a story, such as the life of a minstrel or the life of a specific person or about an event, but was the length of two to three pages rather than the length of a book.
A narrative poem does not need to take several pages to tell the story. A narrative poem can also form from a short poem. A poem that requires only a few couplets can still tell a story within its lines. For example, a short poem about seeing a bird in flight might only require a few lines, but it tells the story of looking up into the sky and seeing the bird's actions or the story of a few minutes. A short poem might not encompass a long tale, but it can capture the story of a few moments, which makes it narrative.