Kashmir Hill, Gizmodo:
Facebook didn’t come up with the idea for PYMK out of thin air. LinkedIn had launched People You May Know in 2006, originally displaying its suggested connections as ads that got the highest click-through rate the professional networking site had ever seen. Facebook didn’t bother to come up with a different name for it.
“People You May Know looks at, among other things, your current friend list and their friends, your education info and your work info,” Facebook explained when it launched the feature.
That wasn’t all. Within a year, AdWeek was reporting that people were “spooked” by the appearance of “people they emailed years ago” showing up as “People They May Know.” When these users had first signed up for Facebook, they were prompted to connect with people already on the site through a “Find People You Email” function; it turned out Facebook had kept all the email addresses from their inboxes. That was disturbing because Facebook hadn’t disclosed that it would store and reuse those contacts. (According to the Canadian Privacy Commissioner, Facebook only started providing that disclosure after the Commission investigated it in 2012.)
Because about one in three people on Earth use a Facebook product, it’s almost a certainty that your contact details have been uploaded by one or more of your contacts, and that the company has the capability to map out at least part of your real-life social network — even if you are not a Facebook member and have never consented to this. There appear to be few laws against this practice despite its obviously devastating privacy impact.