Your ads are eligible to appear when one of your keywords matches someone’s search term on Google or on search partner sites.
But within an ad group, you might have multiple keywords that are similar or overlap in meaning, and could all match a given search term. For example, you might have the keywords plumber course and plumber training course in the same ad group, and both could match the search term training course for plumber. Only one of those keywords can trigger an ad for the search term.
This article explains what happens when your ad group has multiple keywords that could match the same search term. You can also read more about what happens when you have similar keywords across different ad groups.
Having multiple keywords that could match the same search term shouldn’t increase your costs in any way. The set of preferences detailed below determines which keyword is used to enter an ad into an auction. Once the ad enters the auction, it’s then compared with ads from other advertisers, and your cost-per-click is what's minimally required to clear the Ad Rank thresholds and beat the Ad Rank of the competitor immediately below you (if any).
How a keyword is selected
If your ad group has several keywords that could match a search term, the preferences below are used to determine which keyword is used to enter an ad into an auction. The preferences rank approximately in the order listed.
A keyword that’s identical to the search term
If you have a keyword that is identical to the search term, this keyword is preferred for triggering an ad. This is true even if there are other keywords in your ad group that are similar to the search term.
Let's say the search term is plumber course and your ad group includes both the broad match keyword plumber course and phrase match keyword plumber. In this example, the broad match keyword plumber course is preferred because it’s identical to the search term plumber course.
An exact match keyword when the keywords are identical
If you have multiple keywords that are the same, the exact match keyword is preferred for triggering an ad.
If the search term is plumber, and your ad group includes both the broad match keyword plumber and exact match keyword plumber, then the exact match keyword is preferred.
The keyword that has the highest Ad Rank
When several keywords in your ad group match a search term, the keyword with the highest Ad Rank is preferred for triggering an ad.
Let’s say you have these keywords in the same ad group.
Keyword Ad Rank plumber course 1.5 plumber certification course 1
In this example, the keyword plumber course will be preferred because it has a higher Ad Rank.
Exception to preferences
There's a keyword with a higher Quality Score and Ad Rank
One of your keywords has a low search volume status
There's an excessive number of matching keywords
Imagine that you copy an ad group 5,000 times, and now have 5,000 instances of the keyword “plumber” in your account. When a user searches for “plumber,” rather than process all 5,000 instances, we’ll reduce the number of matching keywords. Then, we'll use the preferences described above.