When you assign more than one creative to a line item, you can choose how to optimize between the available creatives to fill an impression. This is called creative optimization or creative rotation. Creative optimization is applied before bidding begins.

You can select which type of creative optimization to use for a line item at any time, however, it will only take effect when you assign:

• More than one video creative to a video line item
• More than one display creative of the same size to a display line item
• A data-driven creative with more than one variant to a display line item

The types of optimization available depend on the type of line item (display or video). Learn more about each below.

Display optimization types

• Even: Creatives of the same size rotate evenly in the display line item. How it works
• Clicks: The creatives expected to attract the most clicks are delivered more often into the ad auction or to your guaranteed deal. How it works
• Conversions: The creatives expected to attract the most conversions are delivered more often into the ad auction or to your guaranteed deal. A conversion tracking pixel is required for this type. How it works

Video optimization types

• Match bidding strategy: Optimize based on the line item's bidding strategy. How it works
• Completions: The video creatives expected to attract the most impressions that were audible and viewable upon completion are delivered more often into the ad auction or guaranteed deal. How it works
• Time on screen: The video creatives more likely to stay on screen for 10 seconds or longer are delivered more often into the ad auction or guaranteed deal. How it works

How each optimization type works

Edit creative optimization settings

1. Open a line item.
2. In the “Line item details” tab, scroll to the "Creatives" section.
3. Select an optimization option from the "Creative optimization" drop-down menu.
   • Note: If you selected Conversions, you’ll need to choose the conversion pixel that will be used to measure these conversions in the “Conversion tracking” section.
4. Click Save.