Tired of being tracked by online ad networks? Then you'll want to give the new Privacy Badger a try. This free add-in for Chrome and Firefox blocks unscrupulous ad networks from tracking you, while still allowing you to use helpful cookies.
Privacy Badger, from the Electronic Frontier Foundation (EFF), is in alpha at the moment, so don't expect perfection. You may well encounter bugs, although I haven't yet found any. You can install it from here.
Whenever you visit a Web page, Privacy Badger gets to work behind the scenes. It examines all the third-party domains that embed code and objects into the page, such as images, scripts and ads. But it doesn't block them at that point, because they may not be tracking you. However, in the words of the EFF's description:
"If a third party server appears to be tracking you without permission, by using uniquely identifying cookies to collect a record of the pages you visit across multiple sites, Privacy Badger will automatically disallow content from that third party tracker. In some cases a third-party domain provides some important aspect of a page's functionality, such as embedded maps, images, or fonts. In those cases Privacy Badger will allow connections to the third party but will screen out its tracking cookies."
Privacy Badger tells you what it's doing as it goes about its work. Its icon turns green if there's no problem with trackers on the site, yellow if there's a third-party domain attempting to do tracking, but that tracking is required for Web functionality. In that case, it will try to screen out the offending cookies and "supercookies." And the icon turns red if Privacy Badger disallows all content from the third-party tracker. You can change its behavior on a site-by-site basis.
Note that at first most or all of the sites you visit will show up as green. That's because it takes Privacy Badger some time to analyze which is tracking you. So a site that starts out as green may eventually turn yellow or red.