First up to bat is site retargeting, the oldest and most common form of retargeting. It works by appealing to consumers who visit the company website or e-commerce store but don’t convert (i.e. spend money) on their first visit.
The idea is simple: online marketers try to pull consumers back to their website or online store by serving company ads to those consumers as they browse the internet.
How do we know where to find these potential customers online? Cookies. Every visitor is tagged with a cookie when they visit the company website. If a cookie-tagged visitor is on another website and the publisher of that site makes its inventory available to ad exchanges, the online marketer can use site retargeting to entice the visitor back to the company website. (Many publishers sell inventory on an online ad exchange and advertisers that use a demand-side platform (DSP) solution can bid on the inventory they want.)
Site retargeting can be improved by taking behavioral data into consideration; online marketers can segment audiences into groups based on product-, service- or information-driven interest by considering webpages and products that consumers have previously visited or viewed. (You can also think about site retargeting as behavioral retargeting.)