Is higher an adverb or an adjective?

"Higher" can function as both an adverb and an adjective, depending on its usage in a sentence. As an adverb, it modifies a verb, adjective, or another adverb. As an adjective, it describes a noun. For example, in "He jumped higher," "higher" is an adverb modifying the verb "jumped," whereas in "The higher shelf," "higher" is an adjective describing the noun "shelf."