When we discuss a poem’s structure, what we are talking about is the form the poem takes and, by extension, how it conveys information and experience to the reader. In the case of “Stopping by Woods on a Snowy Evening,” the poem is presented in quatrains, a total of four four-line stanzas with an AABA rhyme scheme, though the final stanza employs an AAAA structure. In the first, second, and third stanzas, lines one, two, and four share an end rhyme—know, though, and snow; queer, near, and year; shake, mistake, and flake—and in the final stanza, all of the lines end with the same rhyme, providing a sense of closure and even, perhaps, peacefulness: deep, keep, sleep, and sleep.
In addition to the rhyme scheme, Frost has written the poem in iambic tetrameter. This means that each line has four metrical feet, each foot consisting of one unaccented syllable followed by one accented syllable for a total of eight syllables. This regular rhythm, in addition to the regular end rhyme, adds to the mood of tranquility produced by the diction and imagery of the poem. See an example of the rhythm from the first stanza below, in which accented syllables are italicized and metrical feet are separated by vertical bars:
Whose woods | these are | I think | I know.
His house | is in | the vil | lage though;
He will | not see | me stop | ping here
To watch | his woods | fill up | with snow.
In addition to the regularity of the meter, readers might also notice how many monosyllabic words are used. This also contributes to the peaceful, almost hypnotic nature of the poem.