The document defines an adverb as a word that describes or modifies verbs, adjectives, other adverbs, or an entire sentence, but not nouns or pronouns. It states that adverbs often describe verbs by indicating time, place, manner, amount, cause, or degree. Many adverbs end in "-ly" but some do not. The document provides examples of adverbs modifying verbs, adjectives, other adverbs, and entire sentences. It notes that students sometimes misuse adverbs by placing them in the wrong position or overusing certain adverbs. Using carefully chosen adverbs can improve writing by making it more vivid and engaging for readers.