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Published: Dec 04, 2014 7 min read
Wrapped bicycle
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Every week, it seems, there's a new scandal about email passwords being stolen or retail customers' data being hacked by stealthy cyber criminals. Yet such incidents represent only a teeny-tiny slice of how our online behavior is spied upon and used. In the vast majority of cases, our data is tracked and used in entirely legal ways by search engines, social media, retailers, and advertisers. Legal or not, the repercussions of such tracking—and the ads that inevitably follow—can feel like an ongoing privacy violation.

What's more, targeted ads come with the potential of revealing secrets about what people have been searching, browsing, and buying online. While the results are generally not nearly as devastating as identity theft, they can create tense situations. In probably the most notorious example, a father found out his high school daughter was pregnant only after Target had sent her coupons for cribs and other baby products—offers that were based on her shopping history.

This time of year, the relentless stream of targeted (also known as "interest-based" or "retargeted") ads that pop up in banners or on the side of web pages also come with the potential of ruining a holiday gift surprise. Say a mom does some browsing online for presents for her son. Soon thereafter, the items she viewed start showing up in ads on the device that was used, along with ads "inspired" by her browsing history." If and when the would-be recipient hops on the same device, he'll see all of those ads. Without much sleuthing, he'll be clued in about what mom was shopping for, and he'll have a good idea to expect the new Nike high-tops, game console, or whatever come December 25. So much for the big reveal.

It's unclear how often this scenario plays out, but it's a possibility some parents worry about. "I guess you have to pick btw letting your kids use the computer and shopping online, since custom ads follow you and spoil gift surprises," one mom tweeted recently. Last year the founder of Marketing Land wrote at length about his wife's frustrated attempts to stop banner ads from Macy's, ThinkGeek, and other retailers she shopped from popping up on the computer she often shared with her kids.

It's not just parents who worry about blown surprises. One Reddit user recently posted, coyly and excitedly, that her longtime boyfriend had been getting engagement ring ads in his Facebook feed. Surely, she felt, this was an indication that he was getting ready to pop the question. One commenter followed up with a story about a friend whose boyfriend also was flooded with engagement ring ads before he proposed. Then, as soon as she changed her status to "engaged," she was slammed with weight loss ads offering to provide assistance "fitting into your dress." Naturally, the baby-related ads followed after the wedding took place.

"You're stalked with ads related to what you've been shopping for all the time," says Bruce Schneier, an internationally renowned computer security expert and a fellow at Harvard's Berkman Center for Internet and Security. Nonetheless, Schneier thinks it's probably "a rare occurrence" for people to correctly deduce what they'll be getting as holiday gifts based on the ads they see on a shared computer. "When a kid sees an ad for an Xbox, he's probably just going to think I want an Xbox, not Mom got me an Xbox."

For that matter, the presence of these ads is no indication of whether anything was actually purchased. As an Al Jazeera column about "curated" and "retargeted" ads noted, consumers can be "stalked by socks" and other items they browsed while shopping online regardless of whether or not they purchased the goods, or whether they searched for such goods randomly, as a goof, or out of genuine interest. "Personalized ads can be right, but they're often wrong" in terms of being truly appealing to the right set of eyes, Schneier says.

Most e-retailers offer consumers the right to opt out of being subjected to tracking and retargeted ads, but Schneier thinks doing so is a waste of time. Not only are the processes for opting out convoluted and filled with loopholes, there are so many digitized eyeballs monitoring your online activity that successfully negating them one at a time is virtually impossible.

It's much better and more effective, he says, to install a tool such as Adblock Plus (which blocks some or all ads according to filters checked by the user), Privacy Badger (which automatically blocks trackers or ads that it deems to violate "the principle of user consent"), or some combination of several blockers. Others recommend shopping online in private browsing mode; when using Google Chrome Incognito, for instance, the browser doesn't save a record of what sites have been visited, and therefore (theoretically) there should later be no retargeted ads that surface as a result.

If you're dealing with an especially stubborn child or spouse who has a history of noticing what online ads foretell in terms of holiday gifts, you might want to try a different strategy: Spend some time here and there clicking on all sorts of items haphazardly, or purposely browse for things you know he'd absolutely hate to receive on Christmas. The resulting collection of retargeted ads is likely to be so random, nonsensical, and disappointing that it'll throw him off the trail and he'll have no clue what you actually bought.

As a bonus, you'll simultaneously be messing with the retailers, browsers, and other bots that generate these annoying ads in the first place.

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What Should I Do If I've Been the Victim of a Data Breach?