How to block ad tracking on your iPhone - The Verge

A recent article in The Washington Post by Geoffrey Fowler described the author’s shock when he discovered just how many of his iPhone apps were collecting and uploading information about his usage while he slept.

As we all know by now, data is a huge commodity these days. If you use a phone, laptop, or any type of computing device (unless you’re a security expert or a high-end hacker with access to sophisticated blocking tools), you’re paying for your apps by contributing marketing and other info to the companies that supply them.

As Fowler’s article demonstrates, iPhone users are not immune to this, no matter how much Apple assures its customers that it’s looking out for their privacy. But there are some simple ways to minimize the amount of tracking that app vendors can do and the amount of data they can access.

Turn on Limit Ad Tracking

You may not be able to get rid of ads entirely, but you can supply the advertisers with as little info about you as possible. Limit Ad Tracking (LAT) puts the kibosh on what is called “interest-based ads” — in other words, ads that target you based on your search history and other usage stats. Shut it off, and you may get ads that are totally inappropriate for your needs, but at least marketers won’t bombard you with pet ads if you just bought a poodle.

Go to Settings
Select “Privacy”
Select “Advertising” (at the bottom of the Settings screen)
Turn on “Limit Ad Tracking”

LAT isn’t perfect. Marketers can also use a system called fingerprinting, which tracks information about your device type, model, carrier, and other data that is being made public by your browser. Fingerprinting isn’t as useful to marketers as ad tracking, but it can still offer a lot of interesting information. Apple has been working to lock down some of this info, but much of it is still available.

If you want to see how effectively LAT is protecting your phone, you could try taking the Panopticlick test, which is offered by the Electronic Frontier Foundation. It monitors device fingerprinting, among other things. I ran it on an Apple iPhone XS after turning on LAT, and I got a “partial protection” result.

Lock down Safari

If you use the Safari browser on your iPhone, there are several things you can do to make it safer.

Go to “Settings”
Select “Safari,” and scroll down to the “Privacy & Security” section
Turn on “Prevent Cross-Site Tracking” (which means advertisers and other third-party content providers can’t track you from one site to another)
Turn on “Block All Cookies.” The cookies collected by various websites can contain a great deal of information about how you use the site, what info you put into it, etc. By blocking cookies, you prevent that data from being collected.

However, you will probably make things very inconvenient for yourself. Your visits to sites will not be recorded, so, for example, you may not be able to revisit a playlist or repurchase the same T-shirt you bought last year. Some sites will even refuse entry if you don’t allow them to collect cookies. It’s your choice.

Turn off Background App Refresh

According to Apple, the reason to have Background App Refresh turned on is to allow suspended apps (apps that aren’t currently active) to “check for updates and new content.” According to Disconnect, the privacy app company that Geoffrey Fowler cites in his article, it also allows apps to collect marketable tracking data and transmit that data even when you’re not using the app. Interestingly, iPhones ship with Background App Refresh turned on, but it’s not terribly hard to turn off.

Go to “Settings”
Select “General”
Select “Background App Refresh”
You’ll see a list of all the apps that use this feature, and they’re all going to be turned on. Find “Background App Refresh” at the top of the page, and tap on it.
You’ll be brought to a page that lets you enable it for Wi-Fi & Cellular data, for Wi-Fi only, or you can turn it off altogether. Select “Off.”
If you go back to the previous page, you’ll see that all of the toggles for the various apps are completely gone.

You may want to be selective about which apps can work in the background. Some apps might not work well otherwise. For example, Google Photos won’t automatically back up your camera roll unless this feature is enabled. So you can, if you wish, leave “Background App Refresh” on, and then choose which specific apps you want to toggle off.

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