Putting a stop on targeted ads stalking you

Publish: 3:40 PM, August 17, 2018 | Update: 3:40:PM, August 17, 2018

Brian X. Chen

Consider what happens when you shop online for a wristwatch. You peruse a few watch websites and the next thing you know, a watch advertisement is following you everywhere. On your computer, it’s loading in your Facebook feed. On your phone, it’s popping up on Instagram. In your web browser on either, it’s appearing on news sites that have nothing to do with watches. Even if you end up ordering the watch, the ads continue trailing you everywhere.
They’re stalker ads. And they are a symptom of how online ads are becoming increasingly targeted and persistent. Tracking technologies like web cookies are collecting information about our browsing activities from site to site. Marketers and ad tech companies compile that data to target us across our devices. And trackers are now so sophisticated that they can see when you are thinking about buying something but don’t follow through – so they tell the ads to chase you around so you make the purchase.
To the ad industry, targeted ads are better for people than the old days of randomly blasting commercials. “The content isn’t free, so what would you rather see?” said Sarah Hofstetter, the chairwoman for the ad agency 360i. “Ads that are at least trying to be of interest to you, or ads that are spray and pray?”
That’s a fair point. On the other hand, these creepy ads can be extremely annoying, especially when they make incorrect assumptions. They are another example, along with obnoxious auto-play videos and internet trolls taking over internet comments, of how a few bad actors are breaking the integrity of the web.
Stalker ads also raise privacy concerns. A 2012 survey by Pew Research Center found that 68 percent of internet users did not like targeted advertising because they do not like having their online behavior tracked and analyzed. Your browsing history can reveal a lot about you, including your health issues, political affiliations and sexual habits.
Fortunately, I have good news. After several years of interviewing internet companies and privacy experts and testing many web tools, I finally managed to make my stalker ads go away. Before you try to exorcise targeted ads, it helps to understand what’s going on behind the scenes. Let’s say you are shopping online for a blender. You load a webpage for a blender from Brand X, then close the browser. The next time you open the browser, ads for the blender are following you from site to site. They’re also showing up in some of your mobile apps like Facebook and Instagram.
When you visited Brand X’s website, the site stored a cookie on your device containing a unique identifier. Brand X hired multiple ad tech companies to do its marketing. The ad tech companies embedded trackers that also loaded on Brand X’s website, and the trackers took a look at your cookie to pinpoint your device.
The trackers can tell if you are interested in buying something. They look for signals – like if you closed the browser after looking at the blender for awhile or left the item in the site’s shopping cart without completing the purchase. From there, the ad tech companies can follow your cookie through trackers and ad networks on various sites and apps to serve you an ad for the blender.
Ms. Hofstetter said that among ad tech companies, there are good actors and bad actors. The good ones will try to minimize the chances of annoying you by showing you the blender ad only a few times and stopping if they detect that you made the purchase. The bad ones only care to persuade you to buy the blender, so they will relentlessly serve you the ad and not bother to determine whether you already bought it.
Things get extra messy when brands employ multiple ad tech companies that employ different approaches. Perhaps one ad company finished serving you the blender ad after a few times on Facebook. But elsewhere on the web or inside another app, another ad tech company served you that same ad endlessly.