Lightbeam: track the trackers

Lightbeam started as a summer intern project at Mozilla to help people better understand who is tracking them online. The idea is to show people which pages are using which trackers. It then shows you a graph of who is tracking you and where they know you have gone. In this activity you will install Lightbeam, go to several online sites, and look at who is tracking you.

Start by trying out Lightbeam:

Install the Lightbeam Add-on by opening the Firefox Addons page and searching for it. Or by going to the Chrome Web store and searching for it there.
Visit my home page and open the Lightbeam tab. You should only see one dot in the middle of the screen. This is because my server tracked that you visited it, but it doesn't use any 3rd party trackers, so no advertisers know you went there.
Visit The Telegraph and then look at the Lightbeam tab. The Telegraph uses multiple trackers. The ads loaded by The Telegraph also load trackers. You should see the The Telegraph icon appear on Lightbeam along with all the trackers (triangles) it uses linked to it.
Visit The Guardian website and then look at the Lightbeam tab. When you look on Lightbeam you should see that some of the trackers are shared between The Telegraph and The Guardian. This is because these two news sites use some of the same trackers. These trackers now know that you visited both web pages.

Try using Lightbeam on your own pages:

Go to at least 5 of the pages you visit the most often.
Find a page with no tracking.
Find a page with a large number of trackers (at least 30).
Try and opt-out of one of the trackers. Find a Third Party tracker (a triangle) who's name you do not recognize and is tracking you on more than one site. Use a search engine to find the privacy policy of that company. Try and opt-out of tracking by that company.