Poets use a variety of tools to create rhythm or add emphasis to particular words in their writing. One method of developing emphasis is the use of alliteration, which repeats initial sounds of words, either consonants or vowels, that appear within proximity to each other in a poem.
To identify alliteration in a poem, look for pairs or groups of words that begin with the same phonetic sound. Words may begin with identical letters or with letter combinations that create similar sounds. For example, "nest" and "know" create alliteration with similar opening sounds. The words may be directly next to each other in a poem, or they may be within the same line or couple of lines.
Alliteration is most clearly illustrated in popular tongue twisters, like "Peter Piper picked a peck of pickled peppers," or, "she sells seashells by the sea shore." In the Robert Frost poem "Stopping by Woods on a Snow Evening," the line "He gives his harness bells a shake" includes alliteration with the repetition of the letter "h."