Ad retargeting is a digital marketing strategy that involves displaying targeted advertisements to users who have previously visited a retailer's website or interacted with its products online. By using cookies and tracking pixels, retargeting aims to re-engage potential customers, reminding them of products they viewed or showed interest in. This personalized approach keeps the brand in front of the consumer, increasing the likelihood of conversion and driving them back to complete a purchase, thereby maximizing the effectiveness of digital advertising campaigns.