Section: Tracking · Last updated: October 26, 2026
This guide is based on Apple Support “If an app asks to track your activity” (published December 19, 2025), Apple’s developer documentation for the advertising identifier, Apple’s “Apple Advertising & Privacy” page (dated May 11, 2026), and Google’s Play Console Help page “Advertising ID”. Menu names can change between software versions.
Both iPhone and Android phones have an advertising identifier: an ID that apps and ad networks can use to recognise the device for advertising. On iPhone it is called the IDFA; on Android it is the advertising ID provided by Google Play services. The two systems give you different controls. On iPhone you decide which apps may get the ID. On Android you can reset it or delete it.
1. iPhone and Android compared
| Question | iPhone and iPad (iOS 14.5 or later) | Android with Google Play services |
|---|---|---|
| Main control | Apps must ask permission to track; you can allow or refuse per app | You can reset the ID or delete it |
| Where | Settings > Privacy & Security > Tracking | Settings > Privacy > Ads |
| What an app sees after you refuse or delete | All zeros instead of the ID | A string of zeros instead of the ID |
| Does the app still work? | Apple says you can use the full capabilities of the app either way | Google notes apps may have their own ad settings |
2. iPhone: stop apps from getting the ID
Since iOS 14.5, iPadOS 14.5 and tvOS 14.5, apps must ask before tracking your activity across other companies’ apps and websites. Apple’s support page defines tracking as linking information that identifies you or your device from an app with similar information collected by third parties, for targeted advertising or advertising measurement, or sharing it with data brokers.
- When an app asks. Tap Allow or Ask App Not to Track. If you choose not to be tracked, the app cannot access the advertising identifier, and Apple says it is also not permitted to track you with other identifying information such as your email address.
- Change your mind later. Go to Settings > Privacy & Security > Tracking. The list shows apps that asked; switch each one on or off.
- Stop all requests. In the same screen, turn off Allow Apps to Request to Track. You will not see prompts, and every app that asks is treated as if you tapped Ask App Not to Track. When you turn it off, you can also choose whether apps you allowed before must stop tracking or may continue.
Apple’s developer documentation lists when an app receives all zeros (00000000-0000-0000-0000-000000000000) instead of the identifier: when it has not asked for permission on iOS 14.5 or later, when the user declines, or when a profile or configuration restricts access. It also notes one case to check: if you turn Allow Apps to Request to Track off after authorising an app and leave that app’s own switch on, that app can still get the identifier.
Apple says the Allow Apps to Request to Track setting can’t be turned on in some cases, including child accounts or users under 18 by birth year signed in with their Apple Account, accounts managed by a school or business, devices with a profile that limits tracking, and Apple Accounts created in the last three days. In those cases apps that ask cannot access the identifier.
3. Android: reset or delete the ID
| Action | Steps in Google’s help page | Effect |
|---|---|---|
| Reset | Settings > Privacy > Ads > Reset Advertising ID, then confirm | The device gets a new ID |
| Delete | Settings > Privacy > Ads > Delete Advertising ID, then confirm | The ID is removed; apps that ask for it receive a string of zeros |
| Some older Android versions | Settings > Privacy > Advanced > Ads > Opt out of Ads Personalization | An opt-out setting instead of deletion |
Google describes the advertising ID as “user-resettable, and user-deletable”. The delete behaviour came with a Google Play services update that started on Android 12 in late 2021 and expanded to all devices that support Google Play from April 1, 2022.
4. What these controls do not cover
- Ads from the phone maker’s own apps. On Apple devices, ads in the App Store, Apple News and Stocks are controlled by a separate Personalized Ads switch under Settings > Privacy & Security > Apple Advertising. Apple says turning it off may not reduce the number of ads, but the ads may be less relevant. The same screen has View Ad Targeting Information.
- Other identifiers on Android. Google’s developer policy requires apps to use the advertising ID, when available, in place of other device identifiers for advertising. It also allows apps to use other persistent identifiers for non-advertising purposes, and to fall back to them for devices without an advertising ID, as long as they present a privacy policy and follow applicable law.
- Ads themselves. These settings limit tracking and personalisation. They do not remove ads.
FAQ
Q. Is resetting better than deleting on Android?
Google’s page lists both as separate options. Resetting replaces the ID with a new one that apps can still read. Deleting removes it, and apps that ask receive a string of zeros.
Q. Will an iPhone app stop working if I refuse tracking?
Apple’s support page says you can still use the full capabilities of the app whether or not you allow it to track you.
Q. Why is the tracking switch greyed out on my child’s iPhone?
Apple lists child accounts and users under 18 by birth year among the cases where Allow Apps to Request to Track can’t be turned on. Apps that ask on that device cannot access the identifier.
Q. Do I need to do this on a tablet or TV too?
The settings are per device. Apple lists the same Tracking setting for iPad and Apple TV, under Settings > General on Apple TV.
Official sources
- Apple Support — “If an app asks to track your activity”, published December 19, 2025
- Apple Developer Documentation — ASIdentifierManager, advertisingIdentifier
- Apple Legal — Apple Advertising & Privacy (apple.com/legal/privacy), page dated May 11, 2026
- Google — Play Console Help, “Advertising ID”
This article is general information. Menu paths are taken from the vendors’ pages at the time of writing and may differ on other software versions or phone models.