Negative Keyword is a keyword exclusion that prevents ads from showing on unwanted or irrelevant searches.
It matters because paid search can spend budget quickly. Knowing this term helps teams control intent, targeting, bidding, creative, conversion tracking, and lead quality instead of optimizing for surface-level clicks.
Example
A paid training provider notices clicks from people seeking free courses and adds free as a negative keyword. That can exclude searches containing the term. It still reviews related unwanted queries because negative keywords do not automatically cover every synonym or close variant.