Adjectives can be considered a sub-type of adverb.
Adjectives may have unique morphology, requiring an adjective “marker,” or they may appear unaltered. In the sentence structure, they generally appear adjacent to the noun they modify.
One way in which adjectives can often be inflected are the comparative (quick vs. quicker) and superlative (quick vs. quickest). This can be done either at the morphological level or paraphrastically; English can do either (quicker vs. more quick; quickest vs. most quick), although there are some rules about when each from can or cannot be used.