By content keywords
When your keyword (using the “Content” keyword setting) matches a webpage’s concepts or its central theme, your ad is eligible to show on that webpage (also known as an automatic placement). Whether your ad actually shows there is determined by a number of factors, including your language and location targeting.
Example
Suppose you've created an ad group to advertise your car dealership’s latest lineup and you've included keywords like fuel efficient cars and 2015 electric cars. We use contextual targeting to identify and place your ad on Display Network pages that match those keywords.
By topic
When your topic matches a webpage’s central theme, your ad is eligible to show on that webpage. Whether your ad actually shows there is determined by a number of factors such as your language and location targeting.
Example
Let's imagine again that you want to show ads about electric cars that are for sale. You could add the sub-topic Autos & Vehicles > Vehicle Shopping > Vehicle Specs, Reviews & Comparisons to your ad group. This would help you target all pages on the Display Network related to car reviews and comparisons, regardless of whether your exact keywords appear on the page.
