How to Block Ad Trackers on iPhone Using Apple's Privacy Feature

You've probably noticed it: you browse for running shoes on a Wednesday afternoon, and by Thursday morning, those same sneakers are following you across every website you visit, every app you open. It's the digital equivalent of being tailed, and it happens because apps and advertisers are using your device's advertising identifier to build a profile of your interests and sell that information to the highest bidder.

Apple introduced a tool to stop this in 2020, though it didn't arrive on iPhones until the spring of 2021 with iOS 14.5. The feature is called App Tracking Transparency, and it's straightforward in concept: it gives you the power to tell apps whether they're allowed to follow you around the internet. Unless you explicitly grant permission, an app cannot access your advertising ID, cannot share your location with marketers, and cannot pass your data to third parties for the purpose of building targeted ad profiles. The change was welcomed by privacy advocates and privacy organizations, though it provoked sharp criticism from Facebook and other companies whose business models depend on detailed user tracking.

Apple's CEO Tim Cook has positioned privacy as a fundamental human right, and the company has backed that rhetoric with a series of moves designed to give users more visibility into what apps actually do with their data. Before you even download an app, you now see a "nutrition label" in the App Store that lists the categories of information that app requests. It's a small thing, but it shifts the burden of transparency onto developers rather than leaving users to guess.

Using the feature is simple. When you download a new app and open it for the first time, you'll see a prompt asking whether you want to allow that app to track your activity across other apps and websites. You can say no, or you can allow it. If you want to take a blanket approach, you can go into Settings, navigate to Privacy, then Tracking, and toggle off the option that allows apps to request permission at all. Once you do that, every app on your phone will be automatically denied access to your advertising ID, and developers will be informed that you've requested not to be tracked.

For apps you've already installed, you can manage tracking permissions individually. Go to Settings, select the app, and toggle tracking on or off. Or use the same Privacy > Tracking menu to see a list of every app that has ever requested tracking permission and adjust each one separately. Apple requires all developers to ask for permission before tracking; if the company discovers that a developer is ignoring a user's refusal, that developer faces potential removal from the App Store.

But there's an important caveat worth understanding. Blocking app tracking doesn't make ads disappear. It just means you're more likely to see generic advertisements instead of ones tailored to your specific browsing history and behavior. More significantly, preventing apps from accessing your advertising ID—your IDFA—is not the same as preventing all tracking. Developers have other tools at their disposal. They can track you through cookies, through fingerprinting techniques, through the data you voluntarily provide when you log in or fill out a profile. Turning off app tracking is a meaningful privacy protection, but it's not a complete shield. The responsibility still falls partly on users to think carefully about which apps they install and what permissions they grant.