Modifiers change the interpretation or meaning of the words or phrases they are associated with. Some examples of modifiers are adjectives, adverbs, adjective clauses (including relative clauses and appositive phrases), and adverbial clauses. Modifiers are generally optional elements of sentences.
Every elephant has six sets of four teeth that grow
forward as the previous assemblage is worn
down; when the series runs out, often after more than 50 years of
grazing, the animal can no longer forage and dies.
--"Profile: Cynthia Moss," Scientific American