Panopticlick is a research project designed to better uncover the tools and techniques of online trackers and test the efficacy of privacy add-ons.
Interesting website to check if your browser is safe against tracking. Of course they use trackers on this website, since they are required to to this test. But you have to click on the test me button to start the test. That website also educates you about tracking techniques and raises awareness about these forms of trade, which many people are not aware of. I’d withdraw 1 block, because they provide sharing links to trade-based networks like facebook, google and twitter.