Retargeting is a form of online advertising that keeps a brand in front of a prospect after they leave their site. Retargeting works by keeping track of people who visit a specific site with a cookie and displaying ads to them as they visit other sites online. Cookies are planted in a browser based on the sites a customer visits which can include articles, blog posts and social media pages. Brands can follow prospects almost anywhere online once cookied, which is why you may see a competitor's advertisement. That also means it is likely your customer or prospect may see an ad for something completely different based on their browsing history.
In addition, many brands and companies buy online ads across media properties. These sometimes rotate, so you may see a specific ad on one visit and a different ad on another. Brands also pay for a certain amount of exposure, so once that threshold is met (a specific number of impressions or clicks), it may be replaced by another ad.
Unfortunately, OutboundEngine cannot predict or control which ads may appear on a third-party site.