An adverb is a word that modifies a verb, an adjective or another adverb. An adverb describes or gives more information about how, when, where, or to what degree etc something is done. An adverbial is a word, phrase or clause acting as an adverb. Many adverbs end with the morpheme -ly, which converts an adjective X into an adverb meaning something like "in an X manner" - thus "bravely" = "in a brave manner". Other adverbs include intensifiers like "very" and "extremely".