What is a sonnet primarily known for?

A sonnet is primarily known for its specific structure and thematic focus, particularly regarding love. It consists of 14 lines, typically written in iambic pentameter, with a specific rhyme scheme that varies depending on the type of sonnet—Shakespearean, Petrarchan, or Spenserian. The structure not only differentiates it from other forms of poetry but also often emphasizes themes of love, beauty, and the human experience. This rigid framework allows for a deep exploration of powerful emotions and complex ideas within a concise format.

In contrast, the other options describe different types of poetry that do not capture the essence of a sonnet. While nature-themed poems exist, they do not define sonnets, and narrative poems focus on telling stories, which is distinct from the more introspective nature of sonnets. Nostalgic poetry might evoke certain feelings but is not inherently connected to the sonnet's characteristics. The unique blend of structure and thematic content is what primarily identifies a sonnet in the realm of poetry.