The internet is a mysterious and magical place full of Wikipedia rabbit holes, animated GIFs of Ron Paul, and cat videos as far as the eye can see. There are also plenty of ads watching which of those things you are looking at. If that makes you uncomfortable, maybe Ghostery is the browser for you.
Ghostery is a full-featured browser that blocks ads and ad trackers, but includes granular controls to let you decide what works and doesn't work. When you load a page, the ghost icon in the address bar shows you how many ad trackers are on the page. You can allow certain ones, pause blocking, or whitelist a site entirely.
You can use Ghostery completely free, and if you like, you can contribute data about new trackers you encounter to the developers. That's the business model—they track trackers instead of tracking you. Sound okay?