An adverb is a part of speech that changes the meaning of verbs or any part of speech other than nouns (modifiers of nouns are primarily adjectives and determiners). Adverbs can modify verbs, adjectives (including numbers), clauses, sentences, and other adverbs.

Adverbs typically answer questions such as how?, in what way?, when?, where?, and to what extent?. This function is called the adverbial function, and is realized not just by single words (i.e., adverbs) but by adverbial phrases and adverbial clauses.

Adverbs are words like yesterday, now, soon, and suddenly. An adverb usually modifies a verb or a verb phrase. It provides information about the manner, place, time, frequency, certainty, or other circumstances of the activity denoted by the verb or verb phrase.

Adverbs can also modify adjectives and other adverbs.

In English, adverbs of manner (answering the question how?) are often formed by adding -ly to adjectives. For example, great yields greatly, and beautiful yields beautifully. There are also adverbs that do not end with -ly, such as hard in "Asiya worked hard to help her family", or well in "My sister performed well in the examination." Note that some words that end in -ly, such as friendly and lovely, are not adverbs, but adjectives, in which case the root word is usually a noun. There are also underived adjectives that end in -ly, such as holy and silly.