1. Adverbs can be used to modify verbs (actions)
e.g. She sings beautifully.
action (verb) modifies how she sings
2. Adverbs can be used to modify adjectives
e.g. He is very rich.
modifies how rich he is adj.
3. Adverbs can be used to modify other adverbs
e.g. That week seemed to go by incredibly slowly.
modifies the adverb “slowly” modifies the phrasal verb “go by”