This document provides a detailed overview of adverbs, including:
1) Adverbs modify verbs, adjectives, other adverbs and entire clauses. They express manner, place, time, frequency, degree and other elements.
2) Many adverbs end in "-ly" but some words without this ending also serve adverbial functions.
3) Adverbs have comparative and superlative forms to show degree, usually using "-er" and "-est" or "more" and "most".
4) Adverb phrases and clauses also serve adverbial functions and provide details like place and time.