An expansion of how Facebook's user data is employed for advertising purposes is prompting questions over privacy.
This week the firm began rolling out a rebuilt version of Atlas, an advertising server Facebook acquired last year from Microsoft. The technology lets partnered advertisers leverage Facebook members' data to deliver targeted ads to them on outside sites, particularly on mobile devices.
With the rollout, questions have sprung up over the privacy implications for users, and whether it constitutes a new level of intrusion on people's data.
Some experts answered with a resounding "yes." "This expands the surveillance economy into ever more important and intimate aspects of a person's life," particularly when it comes to cross-device targeting on mobile, said Neil Richards, a professor of law at Washington University in St. Louis, who studies digital privacy.
The concept of ads following you around the Internet is not new. People's browsing activity already factors into the ads they see on Facebook. But at the same time, Facebook data is being put to greater use for the purpose of targeting ads on sites far beyond Facebook. That could make some users uncomfortable.
"It's an expansion of Facebook data to the rest of the Web," said Adi Kamdar, an activist at the Electronic Frontier Foundation specializing in consumer privacy issues.
The knowledge that more highly targeted ads will be coming courtesy of Facebook, beyond the social networking site, may spark some to re-evaluate their relationship with the site.
"It pisses me off and makes me unsettled," said one Facebook member, after learning of Atlas. But she stopped short of saying she would quit the site. "I just hate how Facebook has become the main everything, the main communicator of what's going on with my friends," she said.
Concerns like those are part of the reason why ad-less alternative sites like Ello have sprung up.
Atlas also lets businesses connect people's real-world behavior with their activities online. A clothing retailer could use the email addresses gathered from shoppers in a store to deliver an ad to those people who are also Facebook users and on a site or mobile app that serves ads by Atlas. The advertiser can narrow it down further to reach, say, female Facebook users between the ages of 30 and 40 living in Atlanta.
The technology lets advertisers target ads to people across desktop and mobile, and helps Facebook compete against Google by leveraging Facebook's user data across the wider Web.
Facebook says the program works anonymously, so that neither Facebook nor the advertisers know the individual people who are being matched.
But perfectly targeted ads provided by Facebook's technology eventually may scare more users. The retailer Target generated controversy in 2012 after it was revealed to have used purchasing data and demographic information to identify pregnant women and send them promotional materials geared toward their (unborn) babies.
Or some Facebook users might love seeing just the right ad, on just the right device.
Some privacy experts, when asked to comment on Atlas, said they didn't know enough yet to fully gauge the extent to which it raised new privacy red flags. That didn't stop a German consumer group from protesting it immediately.
For others, their biggest questions revolved around what choices users have, if any, to opt out.
"We've heard a lot about the benefits to advertisers, but not as much about controls for users," said Chris Babel, CEO at TRUSTe, a San Francisco-based company that analyzes and provides services around data privacy.
Unfortunately, opting out of tracking through Atlas, or most other systems, is not easy. You can opt out of ad targeting, which would include Atlas, by visiting the Digital Advertising Alliance opt out page. However, that doesn't change what information is collected.
Facebook this past June started offering more controls to users to help them see why certain ads are shown to them, but the controls don't stop tracking altogether.