An adjective modifies a noun. An adjective tells more about how an object looks or feels.
An adverb modifies a verb and tells more about the action by answering the questions how? when? or in what way?
When writing, it is important to use adjectives with nouns and adverbs with verbs.
Good is an adjective because good describes a noun.
This was a good dinner.
You are a good boy.
This is a good movie.
Good might mean tasty or well-behaved or entertaining, but in each case, good modifies a noun. A good dinner. A good boy. A good movie.
Well is an adverb because it modifies a verb and tells how the action happens.
Susan plays the piano well.
My dad is feeling well today.
You have done well on that project.
Well tells how Susan plays, how Dad is feeling, and how you have done.
Fast is an adjective. It refers to the speed of an object.
You have a fast car.
That was a fast trip.
Look at the fast coyote!
In each sentence, the word fast modifies a noun in the sentence.
Quickly is an adverb. It refers to time and how long something takes.
I quickly ate my dinner.
Bill ran quickly through the yard.
Jenny quickly finished her assignment.
In each sentence here, the word quickly modifies the verb by answering the question in what way?
Remember – Good and fast are adjectives that describe an object. Use good and fast to modify nouns.
Well and quickly are adverbs that tell more about the action. Use well and quickly to modify verbs.