Adverbs commonly modify verbs in order to describe how, when, where or why an action is performed. For example, consider the sentence: "He ran quickly." Here, the adverb "quickly" modifies the verb "ran" by describing the speed at which he ran. Consider the sentence: "He ran quickly to get home before noon." Here, the phrase "to get home before noon" acts as an adverbial clause to describe why he ran quickly.
Adjectives are words that modify nouns by describing some aspect of the noun. For instance, "large" is an adjective that can be used to modify many nouns as in the phrases "large tree" or "large house." Adverbs such as "extremely" or "very" can also be used to modify adjectives, as in the phrases "extremely large tree" or "very large house." Here, the adverb is used to give more details about the adjective.
Adverbs can also be used to modify other adverbs. Consider the sentence: "She drove quite swiftly." Here, the adverb "swiftly" modifies the verb "drove" by describing the speed at which she drove, and the adverb "quite" modifies the adverb "swiftly" by describing its nature more precisely.
Adverbs can modify verbs, adjectives and other adverbs. When compared with other parts of speech, adverbs are flexible in that they can often be moved around within a sentence without changing the meaning or creating gibberish. For example, consider the three sentences: "The child quickly ran home."; "The child ran home quickly."; and "Quickly the child ran home." In each case, the adverb "quickly" modifies the word "ran" by describing the speed at which the child moved. It performs this function despite its variable placement within the sentence.