Adverbs modify verbs, adjectives, or other adverbs. They don't decline (no gender, number, or case changes).
Formation from adjectives: • Usually: adjective stem + -ως (σοφός → σοφῶς, "wisely") • Neuter accusative singular can serve as adverb (πολύ, "much")
Common adverbs: • Time: νῦν (now), τότε (then), ἀεί (always) • Place: ἐνταῦθα (here), ἐκεῖ (there), ποῦ (where?) • Manner: οὕτως (thus), καλῶς (well), ταχέως (quickly) • Degree: μάλα (very), λίαν (too much)