Privacy extension to stop sites from from tracking you
The Electronic Frontier Foundation (EFF) is one of the foremost organizations in defending net freedoms and privacy and now it's developed Privacy Badger extension to protect users online.
Privacy Badger works in a similar way to Ghostery in that it blocks advertisers and third-parties from tracking you with cookies. It's extremely easy to setup. Just install the extension and it instantly starts blocking unless you slide one of the bars to stop blocking.
Note that Privacy Badger is not an ad-blocking tool - it's a privacy tool that only allows only those advertisers you have consented to tracking you.