What is the longest style of writing a poem?

There isn't a single "longest" style of poetry. It's more about the form and structure than the length. Here's why:

* Form: Some forms, like epics or long poems, are designed to be lengthy, but there's no hard limit.

* Structure: Even within a form, the length can vary. A sonnet always has 14 lines, but a ballad can be many verses long.

* Modern Poetry: Contemporary poetry often breaks free from traditional forms. Length is less about style and more about the poet's choice.

Examples:

* Epic poems: These tell long, sweeping stories like "The Odyssey" or "The Mahabharata."

* Long poems: Modern examples include "The Waste Land" by T.S. Eliot or "The Cantos" by Ezra Pound.

* Narrative poems: These tell a story, and their length can vary. "The Raven" by Edgar Allan Poe is a short narrative poem, while "Don Juan" by Lord Byron is much longer.

So, there's no single answer. The length of a poem depends on the poet's vision and the form they choose.