About the presence of the FB Like button and Comments widget on a large portion of the web, and what do they do with the data about all the sites and pages thei

About the presence of the FB Like button and Comments widget on a large portion of the web, and what do they do with the data about all the sites and pages their users visit, which is readily available for Facebook to collect, store and use on any site that includes their widgets and even those that don't by way of the Referrer http header in case the next site you visit has FB widgets. Facebook has far more data about the pages you visit than an ISP ever will (to which HTTPS pages are invisible unless they employ MITM techniques). Facebook sees it all...