Facebook is now keeping track of the stores you go to IRL

With all of us constantly carrying around little human-tracking devices in our pockets, it’s hard for companies to resist tapping into that delicious location data. Adweek reports this week that Facebook is going to start using smartphones to track people’s visits to stores:

Today, the social network is adding several new measurement tools that will allow stores to see how many people visit a store location after seeing a Facebook campaign… Facebook’s updates will provide real-time information on the offline response to advertising.

So after the Gap runs an ad campaign on Facebook, Facebook will be able to tell Gap how many of the people who saw their ads actually visited the store. From a retailer’s perspective such a tool is obviously useful, telling them whether a campaign worked and saving a poor Gap sales associate from having to survey every person who walks through the door about what led them there.

There are privacy protections. Facebook doesn’t tell Gap that YOU visited the store, just that a person who saw the ad did. And it only works if you have location services turned on for your Facebook app, which you can change in the “privacy” or “location services” setting on your iPhone or Android.

Facebook already had a more convoluted way of telling advertisers if their ad campaigns worked IRL, which involved partnering with a data broker to track what its users bought in stores. But this is far more expansive and builds on the existing ability to target Facebook ads at a person within 150 feet of a geographical location, say if you’re a Senator trying to influence federal employees or a pro-life organization trying to prevent abortions.

Facebook is far from the only tech giant tracking users’ movements to indirectly disclose them to third parties. Verizon has been doing this since 2012 and Google since 2014. In fact, Google has a public-facing version of the location tracking that’s pretty cool. If you Google a place, say a bar, movie theater or your gym, it will tell you when it’s most and least crowded based on the smartphones it’s historically seen there, in the same way that Google Maps tells you about bad traffic ahead based on location data from smartphones.

But if you’re freaked out about the idea of companies silently using your smartphone to track your movements you do have a way out: turn off location services on your phone… or do the unthinkable and leave it at home.