One of the key factors that determines whether an ad shows up for a particular search query is how relevant the algorithm determines the ad to be to the query. At the same time, by providing users with ads that contain the keywords in their search queries, it’s more likely the user will find the ad relevant and click on it, increasing the click through rate of the ad, which in turn increases the ad’s quality score.
Again, the importance of quality score varies depending on who you ask, but regardless, including keywords contained in the user’s search query in the ad will improve the ad’s performance and therefore the advertiser’s results.
For example, if Zappos had an ad group containing “buy red shoes” and wanted to encourage users to visit Zappos.com to buy red shoes, the ad might look like the ad below:
The above ad would be extremely relevant to someone looking to buy red shoes. However, if a user were looking for blue shoes or Prada shoes, they might find this ad to be less relevant. As a result, ads in ad groups containing blue shoes or Prada shoes should be specifically written to include those keywords to maximize performance, for example substituting “Red” for “Blue” or “Prada” depending on the ad group.