Alliteration is a literary device where words are used in close proximity to each other that start with the same consonant sound, usually at the beginning of words or stressed syllables. It was commonly used in Old English poetry as a metrical device where the initial consonant sounds were repeated throughout lines. While alliteration is still used today for musicality in poems, songs, nursery rhymes and advertisements, it served as an essential part of the structure of Old English poetry where it helped carry the rhythm.