In a perfect PPC world, negative keywords wouldn’t exist. They wouldn’t exist because advertisers would know exactly which user queries were triggering their ads. This can be accomplished by advertising only on exact match keywords, but the result would be substantially low traffic volume.
Thus, there is a necessity to advertise on broad and phrase match keywords. By allowing phrases within queries or similar terms to trigger ads, a whole slew of unknown traffic can now map to your PPC campaign. Unless you’re satisfied with paying for irrelevant traffic, you must now add negative keywords for every irrelevant product, service, company, person, or thing that is even slightly related to the keywords you’re advertising on.
Adding negative keywords is simple. Using search query reports, you can look and see exactly which queries are triggering your ads to show. From here, any queries that you would no longer like to show up for, simply add them as a negative keyword within that ad group or campaign. Negative keywords also have the same match type options as general keywords do, so you are able to block anything from basic themes to entire specific search terms.
It makes sense why it is desirable to add negative keywords to block completely irrelevant traffic. But there is another angle that is becoming increasingly important…
Imagine an advertiser that is selling teddy bears. They have big teddy bears and small teddy bears. They have white teddy bears and black teddy bears and brown teddy bears. You can be certain that this advertiser is bidding on the keyword “teddy bears”, as well as all the variations above. Now, imagine a user that is looking for a brown teddy bear, and types in ‘soft brown teddy bears’. The advertiser assumes that this will map to the keyword “brown teddy bears” and trigger their ad that drives them to a landing page filled with brown teddy bear options. But in reality, this query could have triggered any broad keyword relating to ‘bears’, as well as the generic phrase keyword “teddy bears”. This user could have now been driven to any of the landing pages the advertiser offers pertaining to bears, even to the black/white teddy bears landing page which would now be irrelevant to this user.
More negative keywords. Organizing style, sizes, etc. into ad groups allows negative keywords to now be used directionally. We know ‘brown teddy bears’ queries are relevant to this advertiser, but it should still be used as a negative on other teddy bear colors and generic terms like “teddy bears” to ensure that it is mapping to the most relevant ad group within the account. When we look at large advertisers with hundreds of thousands of different keywords across all match types (this is not unusual), this is essential to keeping keywords within campaigns mapping to the correct queries.