Using the Google Display Network, you can now specific topics to contextually target your ads to pages. With this new option, you can reach from over 1,750 topics and sub-topics to target your ads.
The use of topics to contextually target your ads puts you on a broad targeting channel which will help you quickly connect with a large audience.
When using topic targeting, Google Display Network looks at all the terms on your page to determine the topic. If you choose to use keywords to contextually target your ads, this will target a more specific set of pages.
Both targeting options can be combined to effectively reach an audience across the Google Display Network.
Google Display Network contextual targeting by topic supports the usual ad formats, such as display, video and rich media, as well as the bidding options, including cost-per-click (CPC), cost-per-thousand-impressions (CPM) and cost-per-acquisition (CPA).