Here's why:
* Adverb: It modifies verbs, adjectives, or other adverbs. It tells us *how*, *when*, *where*, or *to what extent* something is done.
* Negative: It negates the meaning of the word or phrase it modifies.
For example:
* "He not went to the store." ("Not" modifies the verb "went" and negates the action)
* "The house is not big." ("Not" modifies the adjective "big" and negates its size)
* "He did not walk very fast." ("Not" modifies the adverb "fast" and negates the speed)
Let me know if you have any other grammatical questions!