So you're wondering, "Why are these ads following me?" Well, those text and banner ads showing up on many of the websites you visit are called "retargeting" or "remaketing" ads. Below are just some of the ads that are currently associated with your browser.
Try refreshing the page to see a new set of ads following you.
These ads following you leverage something called "cookies". Cookies are small files that are generated by the websites you're browsing and are then read by your browser. These cookies help your browser navigate through a website providing additional information. Every time you visit a new website, a cookie is sent to your browser.
When you browse other websites, these cookies let companies like Google know what ads to serve that specifically entice you return to previously visited websites.