- Show customized ads to customers who have previously visited your site
- Allow customers to quickly reorder an item they have previously purchased
- Create remarketing lists without making changes to your existing Analytics snippet
- Create remarketing lists based on custom segments and targets
A remarketing audience is a list of cookies or mobile-advertising IDs that represents a group of users you want to re-engage because of their likelihood to convert. You create remarketing audiences based on user behavior on your site or app, and then use those audiences as the basis for remarketing campaigns.
Learn more here: https://support.google.com/analytics/answer/2611268