Retargeting refers to a digital marketing strategy that involves targeting users who have previously interacted with a website, app, or advertisement but did not complete a desired action, such as making a purchase or signing up for a service. By using cookies or tracking pixels, retargeting displays tailored ads to these users across various platforms to encourage them to return and complete the action. This approach helps increase conversion rates and enhances the effectiveness of advertising campaigns by focusing on individuals already familiar with the brand or product.