Negative keyword

A negative keyword prevents ads from appearing for certain searches that do not fit an offer. Google describes negative keywords as a way to exclude unwanted search terms.[2] They filter advertising eligibility rather than identify a search for which the advertiser wants to appear.

A store selling only new products might investigate whether searches for used items should be excluded. Avoid overly broad exclusions because relevant comparisons can contain the same word. Check negative broad, phrase and exact matching separately from positive keyword matching; Google states that their behaviour differs.[1] Monitor whether useful queries have inadvertently been blocked.