Adverbs are words used to modify adjectives, verbs, and other adverbs, answering questions related to how, where, when, why, and to what degree actions occur. They can be categorized by their function, such as telling how something was done, where it happened, when it occurred, and how often it is done, with common forms typically ending in -ly. The document includes examples and lists of common adverbs, along with their types, emphasizing their integral role in the English language.