The pixel or piece of code that makes this possible is added to the visitor’s browser and is not noticeable. After the user leaves your page, the pixel communicates with your retargeting provider, telling it when to display your remarketing ads. By doing so, the retargeting tool can serve ads only to people who have previously shown interest in your products or services but didn’t convert.
Retargeting is widely used for improving conversion rates, as it targets the bounced visitors, and serves them ads that are tailored for their specific needs. This marketing technique is effective in campaigns whose purpose is to improve conversions and ROI.