When visitors purchase the product (albeit not the same day), the system queries the cookie, and discovers he had previously visited the product page from the banner.
Customizing the site. There are web sites that employ tools that collect information from visitors, such as products that look, those who buy, the banners that prick, etc. (Source: Aboutaam). These data are combined with a database to make a customer profile, and in the upcoming connections show banners or content that is better suited to their interests.