http://kittens.iykpqm7jiradoeezzkhj7c4b33g4hbgfwelht2evxxeicbpjy44c7ead.onion/issues/do-not-track
On the web, tracking is most often performed with cookies —specifically third-party cookies, which come from sites that the user doesn’t even directly visit, but are instead loaded by the “first-party” site the user is on. For instance, a news site may include an advertisement or interactive game from an advertiser server that is able to set cookies on a user’s browser.