App Tracking Transparency Explained

App Tracking Transparency, or ATT, is the iPhone feature behind the pop-up that asks whether an app may track you. It limits one specific kind of tracking, and it does not stop every app from collecting data.

This guide explains what ATT covers, what the prompt changes, how to manage it, and what independent studies found. It follows Apple's pages and published research, checked on October 21, 2026.

The short answer

ATT forces apps to ask before they track you across other companies' apps and websites for advertising, or share your information with data brokers. If you tell an app not to track, it loses access to your advertising identifier.

To stop the prompts entirely, turn off Allow Apps to Request to Track in Settings, Privacy & Security, Tracking. From then on, each app that asks gets the same answer as Ask App Not to Track.

What App Tracking Transparency is

ATT arrived with iOS 14.5. Since then, an app must get your permission before it follows your activity across other companies' apps and websites.

In Apple's definition, tracking means joining information that identifies you or your device from one app with information gathered in third-party apps, websites or other places.

The link counts only when it serves targeted advertising or ad measurement, or when the information goes to data brokers.

iPad and Apple TV have the same control. On Apple TV, the path is Settings, General, Privacy & Security, then Tracking.

What the prompt does when you answer

Apple describes the IDFA as a system advertising identifier often used for tracking. The developer can customize part of the prompt to explain its reason for asking.

You can also open the app's App Store page to see more about how its developer uses your data.

How to see and change which apps can track you

1. Open Settings, then tap Privacy & Security.
2. Choose Tracking.
3. Read the list of apps that have asked to track you.
4. Switch any app on the list on or off.

Only apps that have asked appear there. An app that never showed a prompt will not appear on it.

How to stop all apps asking to track you

1. Open Settings, then tap Privacy & Security.
2. Choose Tracking.
3. Switch off Allow Apps to Request to Track.Off

Apple says apps that want to track you can no longer show a prompt. While the setting is off, an app that asks is treated as if you had chosen Ask App Not to Track.

Apps you allowed earlier are a separate choice. Apple says you can ask all of them to stop tracking, or let just those apps continue. You can also turn each one off in the Tracking list.

Apple says apps that ask while the setting is off cannot access the advertising identifier. Its page does not spell out the identifier's status for apps you chose to let continue, so review that list.

If Allow Apps to Request to Track is greyed out

Apple says the setting cannot be turned on in some circumstances. These are not bugs.

While the setting is off in these cases, apps that ask to track cannot access the advertising identifier.

What ATT does not do

Apple's definition of tracking covers linking data across other companies' apps, websites and locations. Researchers behind a 2022 study reported that Apple's rules exempt first-party tracking.

So an app collecting what you do inside its own service is a different question, and the prompt is not designed to cover it.

ATT does not control Apple's own ads. Personalized Ads is a separate setting under Apple Advertising, and Apple says turning it off may not reduce the number of ads you see.

ATT does not erase information that brokers already hold. For that, see our guide to opting out of data brokers.

ATT also does not show you what apps do. App Privacy Report records how often apps use data such as your location, camera and microphone.

Does App Tracking Transparency work? What independent studies found

Apple says apps cannot access the advertising identifier after you decline. Researchers asked a wider question: whether tracking stopped in practice.

What limits these studies

What the studies add up to

ATT limits access to the advertising identifier and restricts tracking as Apple defines it, but it does not prevent every connection to third-party tracking infrastructure.

Apple Advertising is its own control

Apple shows its own ads in the App Store, Apple News and Stocks. Apple says those ads do not draw on data from other apps.

1. Go to Settings, then Privacy & Security.
2. Select Apple Advertising.
3. Switch off Personalized Ads.Off

Tap View Ad Targeting Information on the same screen to see the information Apple uses.

How to check what an app collects before you decide

Apple points to an app's App Store page to see how its developer uses your data. App Privacy Report adds a log of what the app reaches on your iPhone.

Apple says App Privacy Report needs iOS 15.2 or later and keeps its encrypted data only on your device. It leaves out network activity from private browsing in browser apps.

What we would do

Our view, not Apple's: turn off Allow Apps to Request to Track unless you want to be asked app by app. Apple says apps keep their full capabilities, so the cost is low.

Then use the controls ATT does not provide: location choices, app permissions and App Privacy Report. Our guide to iPhone privacy settings to change covers them.

Frequently asked questions

What happens when I choose Ask App Not to Track?

The app loses access to your advertising identifier, and Apple says it may not track you through other identifying details, such as your email address. The app still works fully.

Can I turn off tracking for every app?

Yes, for new requests. Turn off Allow Apps to Request to Track, and every app that asks is treated as if you chose Ask App Not to Track. Apps allowed earlier need a separate step in the Tracking list.

What if I change my mind?

Return to Settings, Privacy & Security, Tracking, and turn permission on for the app. Apple says you can grant or withdraw permission at any time.

Will apps stop working if I decline?

Apple says an app keeps its full capabilities whether you allow or decline tracking.

Does ATT stop data brokers?

It covers sharing your information with data brokers for tracking as Apple defines it. It does not remove data brokers already hold, so use the opt-out steps in our broker guide.

Does ATT apply to Apple's own ads?

No. Personalized Ads under Apple Advertising is a separate setting.

A quick checklist

• Go to Settings, Privacy & Security, Tracking.
• Switch off Allow Apps to Request to Track, or go through the app list.
• Choose whether apps you allowed earlier should stop tracking.
• Check Apple Advertising and decide on Personalized Ads.
• Switch on App Privacy Report to see what apps use.

Up nextSignificant Locations on iPhone: what it storesAnother setting people overlook is location history. Our guide to Significant Locations on iPhone explains what it stores and how to clear it.→