“Usually”, above, is an adverb.

This is a bird’s eyeview for the adverb:

Positive adverb: Jenny works hard and carefully.

Comparative adverb: Kate works even harder and more carefully than Jenny.

Superlative adverb: Pam works (the) hardest and most carefully.

Adverb of degree: Jack is quite short but rather chubby.

Adverb of frequency: I never smoke but I sometimes drink alcohol.

Adverb of manner: Anne drives slowly but safely.

Adverb of place: He ran away. She lives abroad.

Adverb of time: Today he is still unwell.

Interrogative adverb: Why/when/where/how did he go?

Relative adverb: The town where I was born.

Sentence adverb: Hopefully she’ll come.

She definitely ought to.

examples:

We moved very quickly down the stairs.

(very is an adverb that modifies the adverb quickly)

We ate an extremely scrumptious dinner at the restaurant last night.

(extremely is an adverb that modifies scrumptious which is an adjective that modifies the noun dinner)

The one you are probably most familiar with :

The mouse scurried hastily across the basement floor.

(hastily is the adverb here that modifies the verb scurried).

Many adverbs are easily spotted because they end in “-ly”.

He quickly ran to the supermarket.

Adverb: quickly

Verb: ran