Riccardo Esposito discusses the importance of retargeting (also known as remarketing) in online advertising, a technique that targets users who have previously shown interest in a product or service by visiting a website. The article explains the difference between retargeting and remarketing, the latter often involving email marketing to reach users. It highlights the effectiveness of retargeting campaigns in increasing conversion rates and the necessity of multiple site visits before a user completes a purchase. The article also covers the difference between static and dynamic retargeting, the use of email campaigns for remarketing, and how to utilize Facebook and Google for retargeting ads. Esposito emphasizes the importance of setting clear objectives, monitoring ROI, ensuring quality in ad content, and understanding user behavior to avoid cart abandonment.