Frost, unlike his great contemporaries such as T. S. Eliot, Ezra Pound, Wallace Stevens, and William Carlos Williams, never stopped using traditional forms in his poems. He continued using strict meter and rhyme forms throughout his career, famously remarking that free verse - poetry written without strict meter or rhyme - was like "playing tennis without a net."

"Birches" is written in blank verse. Blank verse is a kind of unrhymed, metered poetry that is very common in English. It consists of five "feet" (syllable groups) of two syllables each, in which the first syllable of each foot is unstressed and the second stressed: dah-DUH. This stress pattern is called iambic pentameter: an iamb is the two-syllable foot just described, and pentameter simply means that there are five feet in each line.

Blank verse has a long and glorious history in English poetry. It is the verse pattern...