This is a question from the proposal phase.
What is the difference between 좋다 and 좋아하다?
How do we distinguish between them?
Now I'm really only beginning to learn how to "transform" words, and I don't know what adjectives can use this and what cannot, but as far as I know things to do with feelings can use this derivation:
In addition, for a sentence like the "I like you" example above, for a transitive verb, it can be said that if
A가 B를 C아/어하다
then it is equivalent to say
A는 B가 C다
Note, however, that the former is used if A is a third person, otherwise the latter form is used.
Basically, '좋다' is a predicate. It can be used as an adjective, an adverb, and a verb. As others told, basically 좋다 is an adjective in many cases. However, if you try to use it to describe a behavior, then it is verb. For example,
나는 네가 좋다. (I like you.)
It can also be felt like an adverb when you translate the sentence in English.
나는 기분이 좋다 (I feel good.)
And of course, like this, it can be used as an adjective. 이 제품은 좋다. (This product is good.)
What you have to know is, Korean grammar usually classifies words with their role, not with their form or notation.
In contrast, 좋아하다 is obviously a verb. It can only be used as a verb. This is because of its ending, -하다.