How do I add and exclude topics?

Add topics

To reach a large audience that's looking at content relevant to your business, you can contextually target pages about a specific topic. Here's how:

Go to the Topics tab. If you don't see this tab in your account, click the drop-down menu next to the tab bar within the main Campaigns tab, select the "Topics" option, and click OK to enable it.
Click the +Add topics button.
Select your campaign and ad group.
Select as many topics and subtopics as you'd like by clicking the add link next to each topic and subtopic. The added topics and subtopics appear in the "Selected topics" column.
Click Save.

Notes:

When you target a top-level topic, you also target all the related subtopics. However, we recommend adding the subtopics for bidding and reporting control.
Adding all the subtopics isn't the same as adding the top-level topic. There are pages that won't be targeted if you add only the subtopics to your ad group. We recommend adding the top-level topic as well.

Learn some best practices for targeting by topics that can help your ads appear on the most relevant webpages for your product or service.

Exclude topics

If you'd prefer your ads not to appear on webpages about specific topics, you can exclude those topics. Just follow these steps:

On the Topics tab, click the Exclusions link at the bottom of the table.
Click the Add exclusions button in the "Ad group level" or "Campaign level" section, depending on the type of exclusion you'd like to add.
Type a term or phrase in the search box to find a topic to exclude, or simply click each topic to see the subtopics you can select. Click add next to the topics and subtopics you'd like to exclude. The selected topics appear below the "Exclude topics" panel.
Scroll down and click Save.

Note: keep in mind that this type of topic exclusion is different from the Site and Category Exclusion Tool:

The tool allows you to exclude a sub-set of topics only (if you want to avoid webpages potentially considered sensitive or mature).
Topic exclusion within the Topics tab gives you more control over where your ads appear, as you can select from a wider variety of options what types of pages you'd like to avoid for your ad.