Here's why:
* Adverbs describe verbs, adjectives, and other adverbs. They tell us *how*, *when*, *where*, *to what extent*, or *how often* something is done.
* Adjectives describe nouns. They tell us more about the noun they modify.
* Adverbs can modify adjectives to provide more detail about the quality or characteristic the adjective describes.
Here are some examples:
* Adverb modifying an adjective:
* "The extremely tall building" (extremely modifies the adjective "tall")
* "He was completely exhausted" (completely modifies the adjective "exhausted")
* Adverb modifying an adverb:
* "She walked very slowly" (very modifies the adverb "slowly")
* "He ran incredibly fast" (incredibly modifies the adverb "fast")
Let me know if you have any other questions about grammar!