Targeting lets you define specific criteria for your ads to reach the right audience, on the right platforms, and in the right contexts. This helps optimize ad performance. You can set up the following targeting criteria:

• Targeting: in the Targeting section, you can define criteria that control the audience, placement, and delivery of your ads. This lets you target specific publishers, devices, environments, and other factors to ensure your ads reach the right audience in the desired context. 
• Supply: in the Supply section, you can define specific publishers, domains, and apps to target. 
• Site list: a site list consists of a collection of domains and apps that you can either include, specifying where ads will be displayed, or exclude, specifying where ads won't appear. 

For more information, see Set targeting criteria.