"Alliteration" refers to the repetition of the consonant sounds (identical initials) at the beginning of words. These words are situated close to each other or are neighboring. For example:
humble home
“She sells seashells by the sea-shore.”
As noticed, the series of words start with the<u> same consonant sound</u>. The first example starts with the consonant sound "th" while the second example starts with the consonant sound "sh."