retargeting or some other ad technique Google makes a significant portion of revenue from their content network, which are ads that are displayed on other webs

retargeting or some other ad technique Google makes a significant portion of revenue from their content network, which are ads that are displayed on other websites. They also offer remarketing, which allows an advertiser to display their ads across the content network to people who have visited the advertiser's website. At the very least, remarketing requires tracking.