AdRoll works with Facebook by allowing businesses to run retargeting ads on the platform. When a user visits your website, AdRoll tracks their behavior using cookies. After they leave, AdRoll shows them personalized ads on Facebook. This helps keep your brand in front of potential customers and increases the chances of them returning to your website. AdRoll integrates with Facebook Ads Manager, so you can manage your campaigns and track performance from one platform. You can also target specific audiences on Facebook based on their interactions with your website, improving ad relevance and engagement.