> Advertisers know every last intimate detail about a Facebook user’s life and can thus market to him or her with extreme precision based upon the social graph Facebook has generated.
> …
> Your friends see that you support their message, but what neither of you see is what happens with the data generated with each and every Like—data that are captured, dissected, and sold to marketers and data brokers around the world.
Companies like Facebook (and Google), prominent and huge in online advertising, do not help "Advertisers know every last intimate detail about a Facebook user’s life". These companies guard their users' data and keep it close to themselves so that they have the advantage of tracking, building profiles through other websites (with like buttons and commenting) and their own properties, and targeting the users with ads that the users are more likely to engage with (and thus make more money). They may share information with the ones paying to advertise on these platforms, but that's only in aggregate and does not include personal information of users. This may change in the future (more so with the changes in WhatsApp's policy).
Facebook has a help page titled "Common Myths About Facebook" [1] that states that advertisers do not have access to personal information (unless the user permits it) and that it does not sell users' information to anyone. Similar and longer explanations are on a note titled "Ad Targeting and Your Privacy: Keeping you informed on ad targeting updates" [2]
and Facebook's Data Policy. [3] (In all these pages, do a 'find on page' or use Ctrl+F or Cmd+F to look for 'advertisers' to reach the relevant points quicker)
Either Facebook is blatantly lying (which is a possibility I would seriously consider) or the author of this book has misunderstood things…or it's a mix of these two.
I do not like online tracking and the collection of personal and behavioral information online (with the resulting targeted ads). I do not like companies that engage in these. However, for now, leave aside unethical behavior by their employees or the possibility of being hacked and having information stolen. With that context, can anyone with more knowledge clarify why people keep saying that personal information is shared with advertisers (or worse, sold to them) by these companies? I can understand that personal information may be shared with various governments or government organizations.
[1]: https://www.facebook.com/help/369078253152594/
[2]: https://www.facebook.com/notes/facebook-and-privacy/ad-targe... (Dated February 27, 2013)
[3]: https://www.facebook.com/full_data_use_policy (Dated January 30, 2015)