Remarketing
Have you noticed that having visited certain websites, ads promoting products or services from that website follow you around the internet?
This is called remarketing.
You have probably seen 'Accept cookies' notices within websites.
Sometimes, the notices are so large that you cannot read the content behind the notice.
Therefore you either have to leave that website or accept cookies.
Once cookies have been accepted, they are stored in the visitor's browser (i.e. Chrome).
The visitor looks at another website (which runs ads) and they may see ads that relate to the previous 'remarketing' site....