A search term report shows what people are searching for when your ads are shown. With this impression, ad position and click data, you can refine your keyword and negative keyword lists for your ad groups. Learn more about keyword match types, and how to use them.
Here's an example: Let's say you're a small software company with an ad campaign using the keywords software development, software download, and school software. You run a search term report, and discover that the search term educational software download generates a lot of impressions for your ad. Impressions can lead to clicks, which can lead to sales, so you decide to add this keyword to your keyword list. The search term antivirus software downloads also results in many impressions, but your company doesn't make antivirus software. So you decide to add that term to your negative keyword list to filter out impressions you know won't help you.
A Search term report includes only search terms that have had a significant number of clicks in the specified time period. This means the number of impressions listed in a search term report might be just a fraction of the total impressions seen in other performance reports (e.g., Keyword Performance report, Campaign Performance report, etc.).