You may have noticed that when you look at products on a search engine, that same product appears as an advertisement in your social media and other sites you visit. Many search engines provide advertisers with tools for evaluating the impact of different keywords or phrases. These tools typically “track” user behavior patterns and associate products for sale by companies that subscribe to and pay for their services to help identify potential customers. On the other hand, there are also ad-blockers that block this type of communication.
The ecosystem of online mass media advertising consists of one giant market instead of only a web browser or only a social media representation. It converges all the online marketing into one aspect to reach the masses. Therefore, constraints should be set in a well thought out general agreement between the affiliate and the advertiser to not impose on the users privacy. This is a good read on internet opacity/nontransparentcy. https://plato.stanford.edu/entries/ethics-search/#SearEngiBiasProbOpac