Richard Stallman Button Quotations

Facebook mistreats its users. Facebook is not your friend; it is a surveillance engine. For instance, if you browse the Web and you see a 'like' button in some page or some other site that has been displayed from Facebook. Therefore, Facebook knows that your machine visited that page.

If there is a Like button in a page, Facebook knows who visited that page. And it can get IP address of the computer visiting the page even if the person is not a Facebook user.