Remarketing allows advertisers to target ads to visitors who previously visited their website but did not make a purchase. It works by placing cookies on visitors' devices to track them as they browse other sites, then showing them targeted ads. Remarketing ads can be text, images, videos or animations displayed on websites. It is flexible and cost-effective at reminding visitors and increasing brand awareness. To be effective, remarketing ads should be highly relevant and offer incentives for visitors to return to the website.