Adverbs are words that modify verbs, adjectives, other adverbs, phrases, or clauses. They indicate manner, time, place, cause, or degree and answer questions such as "how," "when," "where," or "how much." Adverbs are typically formed by adding "-ly" to an adjective. The document provides examples of adjectives and their adverb forms. It then gives exercises to identify adverbs and their modifiers in sentences.