Facebook, that covers more than 800 million active users, as well carries on to track closely the millions of unregister users who visit other than social networking websites, whatever the reason of visiting a webpage for only once.
All this done using cookie technology by the company like other companies Google, Adobe, Mircrosoft, Yahoo and others in the marketing business, Said by Facebook Engineering Director.
Whenever anyone signs in to Facebook, it places in a “session cookie” and a “browser cookie” into user browser. If someone without logging on just visits Facebook it places a browser cookie.
Now every time someone visit the site that is using Facebook tools, that cookie work in combination with the Facebook cookie from that time and URL someone is viewing.
The distinctive properties like the IP address on someone, OS, screen resolution and the version of browser tracked as well by Facebook.