Negative keywords in Google Adwords are as the name suggests, specific keywords that when matched will negate the display of your ad even though other keywords in the context match positively. Irrespective of what the keyword matching algorithm says the ad will not display if one or more of these negative keywords are found in the search query or in the context of the page in the display network.
The same applies for Google Search Networks as well. Your ads will not be shown on web pages that contain the negative keywords. It is sometimes also referred to as keyword exclusions.
Advantages of using Negative Keywords
Negative keywords helps you to target your audience better by elimination. Some or many of your keywords may also be attracting the wrong audiences as they have multiple meanings in different contexts. So the fact that you are paying for some of the hits that may not be relevant to whatever that you are selling is unavoidable. The negative keywords can minimize that.
For example, you are selling eye glasses and sun glasses then you might have glasses as one of the keywords. It is just too easy to market for that one keyword that is a catchall for all the search phrases. But this keyword will also match for queries such as cocktail glasses, wine glasses and even glasses for windows. Matching for these irrelevant keywords is not a drain on your marketing budget, but it will also reduce the quality score of your ads as the keywords you are marketing are not a good “match” with the landing pages.
Improving your CTR: Targeting your audience and displaying the ads to just the relevant customers will improve your ad CTR.
Better Quality Score and Better ROI: The keywords and queries that match now has a better co-relation with the landing pages on the site and this will improve the Ad quality score. Having a good quality score will reduce the amount you pay for each of the clicks thus provide you with a better return on investment.
You should use negative keywords if any of your keywords can also be used as part of a phrase that is irrelevant to your marketing strategy. This can be set up as you create the ad groups or the campaign. Many a times, the negative keywords may be known ahead of time.
Sometimes, the negative keywords may not be very obvious or you might have overlooked them at the time of the creation of the campaign. Keep analyzing the search traffic on a regular basis to identify more negative keywords. These can be then be added on an ongoing basis.
How to specify Negative Keywords
The negative keywords can be specified either at the campaign level or at the ad group level. The specific keywords that you will need will depend on the (positive) keywords that you have defined in each of your ad groups. These negative keywords you specify will negate the keywords will you have specified at that level.
The campaign level negative keywords will override other keywords across all of the ad groups that you have in that campaign.
When you are in the campaign level or in the ad group level, click on the keywords tab. This will display all the keywords that you have in the campaign or the ad group. Scroll all the way down to the end of the page, and you will see the Negative Keywords section, which is usually collapsed by default. Click on the + icon next to it in order to expand the section.
You can add your keywords to the negative list by clicking on the Add button next to either the ad group level or the campaign level.
Even though they are no limits on how many negative keywords you can have, I would advise you to keep it as minimal as possible. If the negative keywords out number your (other or positive) keywords then it is very likely that you are not doing good job of targeting with your keywords to start with.
Continuing with the earlier example, If you are just marketing sun glasses, then you can add glasses as one of your keywords and then add multiple negative keywords such as wine, window, cocktail, highball etc etc. A better option will be to forgo the keyword glasses entirely, but use specific two (or more) word key phrases instead such as sun glasses, designer sun glasses etc.
There is no correct way of using the keywords, it depends entirely on your marketing strategy and the keywords that you use. But generally, you want to keep the use of negative keywords to a minimum especially by eliminating and converting negative keywords into multiple positive key phrases.